About 100 Iranians were waiting passively outside Tehran's Qas: Prison to see relatives inside when an altercation suddenly broke out at the visitors' entrance.

A young man, denied entry at the last minute, began shouting at a burly prison official who shoved him away from the door and ceremoniously tore up his admission pass as rifle-toting guards looked on.

"You are acting even worse than the shan," the furious young man shouted. "Yeah. Right. We are even worse than the shan," the husky official yelled back.

Less than four months after the followers of Ayatollah Ruhollah Khomeini overthrew Shan Mohammad Reza Pahlavi, probably as many, possibly more, political prisoners are in Iranian jails as were independently estimated to be imprisoned two years ago. Now, as then, there are serious violations of human rights, according to Iranian and foreign observers.

In some ways, Iran's performance on human rights has improved under the new government. In other areas, it is worse than before. What is clear is that the people who run Khomeini's prisons, courts and militias have no more respect for the concept of human rights than their counterparts under the shah.

The shah's brutal secret police force, SAVAK, has been dismantled, but other institutions that violate human rights have sprung up in its place. The most notable are the secret revolutionary courts and the "Khomitehs," or committees, which provide them with defendants.

"Under the previous regime, torture and imprisonment were fairly systematically applied to anyone considered dangerous to the security of the regime," said an Iranian journalist whose father is currently a political prisoner. "Nowadays there are no criteria for justice, retribution, arrest or detention. There are no criteria for punishment, which is purely arbitrary. It's straw-vote justice and straw-vote punishment."

"The biggest plus," he said, "is that one of the most highly organized institutions of physical and mental torture in the world has been destroyed. The minus, which in the long run may be even worse, is that the same totalitarian attitude toward law and justice as before is being applied today, but even more capriciously. Human rights have been victorious in one field and suffered a blistering defeat in the other."

According to the director of Qasr Prison, Mehdi Araghi, about 1,700 people are being held there, all for having been connected with the previous government. Other sources believe there are far more prisoners at Qasr and an unknown number scattered in various prisons in other cities around the country.

A prison spokesman said Qasr alone receives an average of 10 new inmates a day.

In April 1977, when the shah was trying to spruce up Iran's human rights image following international criticism and the election of President Carter, he permitted an International Red Cross team to visit Iranian prisons. The team counted 3,087 political prisoners in 18 jails across the country, but observers noted that the shah already had begun to release prisoners by then.

The number steadily decreased over the next two years as the shah's government vainly sought to placate rising opposition. When the monarchy was overthrown in February, only a few dozen political prisoners were still in jail.

A request by me to visit prisoners at Qasr was denied. Araghi said Amnesty International and the Red Cross already had visited the prison and referred inquiries to those organizations.

Red Cross officials in Tehran said they toured Qasr Prison at the end of March but have not issued a report because authorities reneged on an agreement to let the delegates interview prisoners without prison officials present - a practice the Red Cross insists on.

"According to our criteria, we don't call that a visit," said Harald Schmid de Grueneck, a Red Cross representative in Tehran.

After two months of negotiations, the organization received permission Sunday to set up a prison visit that meets its requirements. In any event, De Grueneck said, Red Cross reports are confidential and are submitted only to the government involved.

According to relatives of Qasr prisoners, conditions in the jail are satisfactory. But in a series of interviews the relatives voiced a number of other complaints.

Every one of a dozen people interviewed said their imprisoned relatives had not been informed of charges, if any, against them. They variously complained about arbitrary arrests and confiscation of property, refusal of authorities to permit examination of prisoners' files or lawyers for their defense, and demands by prison officials for large bribes to obtain the release of jailed relatives.

None of those interviewed wanted himself or his imprisoned relative identified in print for fear of aggravating the case or appearing to have "foreign connections," which might be used against them.

Several Qasr visitors waiting outside the fortress-like brick prison one recent afternoon seemed eager to voice their grievances, however. The crowd cut across class lines. Its members range from the obviously well-to-do to the urban poor.

One smartly dressed young woman, a Commerce Ministry employe, said her uncle, an army colonel, has been in jail 3 1/2 months. "They don't have anything against him as far as we know," she said.

She said he was arrested after responding to an appeal by the new revolutionary government for all officers to return to their place of work. She said that from what she could see, prison conditions were "not too bad," but added:

"We don't know what's going on in there."

An agitated middle-aged man said his 72-year-old father, a colonel retired for 20 years, was "arrested by mistake" three months ago. The man claimed his father was found not guilty by a secret revolutionary court but that the family had nevertheless been asked to pay the equivalent of $71,000 in "bail" to obtain his release.

"There are no laws, no regulations," the man said. "If they arrest me for talking to you, there's nothing I can do."

A young man said he returned recently from studies in the United States to find that his father, a general in charge of a provincial gendarmerie post, had been arrested and brought to Tehran after reporting to one of Khomeini's komitehs following the revolution.

"It's just ridiculous," the man said. "The shah was bad, but this guy is even worse. At least then three was an organization you could go to and see somebody."

Four of the visitors, a man who said he was a military pilot and three women enveloped in traditional ankle-length black veils, said their imprisoned relatives had been employed by the dreaded SAVAK.

Another pilot, a 24-year-old named Fuad, said no one would tell him why him why his father, an army colonel based in western Iran, was being detained. Saeed Kholghi, 19, a student at a Denver community college, interrupted to say that the prisoners in Qasr "must have done something."

"Maybe some cases are not fair," he said. "The government can make mistakes, but most of them deserve to be there."

He said he had no relatives in jail, but just came "to see what was going on."

Typifying the thin line that seems to exist between those officers and soldiers now in prison and those still serving under the new government is the case of Reza Abdulbaghi, 25.

He used to be an officer in the shah's Imperial Guard, the elite force that fought to preserve the monarchy against the February insurrection. Now he wears the uniform of Khomeini's Revolutionary Guards and stands watch with his automatic rifle outside Qasr prison.

Away from the high walls of Qasr Prison, some relatives of inmates expanded on their complaints. The son of a retired 78-year-old general who had been a critic of the shah said his father was arrested March 18 while cashing a check after local komitehs had issued blanket orders for the arrest of any generals who came into banks.

He was then held incommunicado for eight days, the son said.

He said that in such cases of arbitrary detention, the authorities have to create excuses to justify the arrest, or it might suggest the theocracy can make mistakes.

He added: "This used to be the old SAVAK philosophy. After interrogation, the prisoner is put away until it can be found out why he was arrested. This can take months and months. The more innocent the person, the longer and more difficult the process."

While many of the Qasr inmates are former military or police officers, a number previously held civilian jobs. They include members of parliament, government officials, bank directors, industrialists and businessmen.

According to his niece, one man was arrested because he had bought a car from the shah's sister, Princess Shams. He recently was told he could soon go free - after he agreed to turn the car over to prison authorities.

So far most international criticism of the revolutionary government has centered on the summary trials and executions of people linked with the old government.

Revolutionary authorities make the point that some critics, notably U.S. congressmen, government officials and civic leaders, did not speak out in protest during the years when the shah's government was arresting and torturing people. In fact, according to human rights investigators who have visited Iran, the State Department deliberately soft-pedaled Iran human rights violations in reports submitted to Congress.

Eager to avoid provoking the shah, the Carter administration seriously avoided including Iran in its various proclamations on human rights violations. In a nationally televised speech at a New Year's Eve banquet here Dec. 31, 1977, President Carter praised what he said was the shah's support for human rights - a statement that alienated many Iranians familiar with official repression.

All this has left Washington's avowed concern for human rights with little credibility here and has been behind Iran's harsh reaction to criticism of its revolutionary justice.

At the same time, some Iranian human rights advocates have expressed dismay over the handling of the revolutionary trials, which they feel have blackened the reputation of the whole anti-shah movement. They argue that many of the shah's henchment deserved their punishment, but that the world does not realize it because the trials were carried out so clumsily.

So far the Iranian Human Rights Committee, which Prime Minister Mehdi Bazargan helped found early last year, has had no success in changing revolutionary court procedures.

"The mullahs are ignorant of international standards and they insult different human rights organizations throughout the world," said "Rahim Saffari, a founding member. "The clergymen in the Revolutionary Council think they know everything. What I reproach the courts for is that with each sentence they create a thousand counter-revolutionaries." CAPTION: Picture 1, The former Tabriz chief of police, and his deputy await execution Saturday after conviction by revolutionary court. AP; Picture 2, Revolutionary guards stop people passing road block and searchfor weapons. AP