Iran's Foreign Minister Sadegh Ghotbzadeh accused the United States today of blocking the formation of a United Nations commission of inquiry into human rights violations under deposed shah Mohammad Reza Pahlavi.

Ghotbzadeh said U.N. Secretary General Kurt Waldheim had accepted the idea of attempting to establish the commission when he visited Iran recently.

"He accepted the idea, but when he went [back] to the United States he was apparently stopped by the Americans," the foreign minister said. "Waldheim was blocked by American interests. He was happy about it (the commission) when he left here."

Ghotbzadeh said Waldheim had been expected to take the initiative and form a commission of inquiry into alleged violation of human rights and inhuman acts in Iran under the shah. "So far he hasn't done it."

However, the foreign minister said the establishment of the commission was meant to be a step on the road toward a solution to the U.S.-Iran crisis.

[In New York a U.N. spokesman "categorically" denied that there had been any agreement about a commission. Waldheim, meanwhile, was scheduled to depart for New Delhi to attend a U.N. industrial development conference. The spokesman said Waldheim had no plans to return to Tehran in the near future, quashing speculation that he may stop over in Iran en route to New Delhi.]

Speaking at an early morning press conference, Ghotbzadeh indicated no softening in Iran's public conditions for the release of the American hostages held since the U.S. Embassy in Tehran was seized by militant students on Nov. 4.

Instead he stuck to a statement made earlier this week that the "liberation of the hostages" should take place simultaneously with the return to Iran of the shah and his wealth.

"These three things can be done simultaneously. There is no point discussing one aspect of it without doing anything about the other aspects."

Ghotbzadeh, a candidate in Iran's first presidential elections set for Jan. 25, called his press conference to coincide with his departure for Shiraz, where he was to spend a day on the campaign trail.

Ghotbzadeh also dismissed accusations that the American hostages were being held in Iran under extremely poor conditions as "propaganda of Zionism and international imperialism."

He said he had not seen a letter from a hostage published in yesterday's Washington Post which complained about the conditions under which the captives were being held.

"However, I am absolutely sure this type of accusation is absolutely false," he said, adding that it was not the first time such accusations had been made.

He said there had been a buildup of accusations about the conditions under which the hostages were held before the Christmas visit to Iran of American clergymen. The clergymen conducted Christmas services inside the U.S. Embassy compound here.

"There was talk of the conditions, and then it all calmed down a bit. Now it is starting again. This is the propaganda of Zionism and international imperialism," he said.

Although a number of independent observers have visited the embassy and have talked to hostages, there has been no thorough independent examination of the conditions under which the hostages have lived since the embassy was seized.

About 500 Iranians braved near-freezing temperatures outside the American Embassy in Tehran tonight to demonstrate support for rival candidates in next week's presidential elections.

The majority of the demonstrators carried posters supporting Iran's Finance Minister, Abol Hassan Bani-Sadr, who is widely considered to be the front runner among the 100 presidential hopefuls.

In a further campaign development, the influential Theological Society in the holy city of Qom announced its support for Hassan Habibi, a member of Iran's ruling Revolutionary Council.

Habibi, 43, said in an interview in the weekly magazine The Iranian that the Revolutionary Council, at least collectively, had no control over the militants at the U.S. Embassy.

Meanwhile, Tehran's new spiritual leader, Hojotoleslam Seyyad Khamenei, a member of the Revolutionary Council and deputy defense minister, strongly supported the rebel Moslem forces in Afghanistan fighting Soviet troops there.

In a prayer service at Tehran University, he said the Islamic Revolution in Iran would not achieve real victory until Afghanistan had been liberated from the Soviet intruders.