The political atmosphere in Pakistan has become increasingly tense following a series of assassination attempts against government officials and incidents of sabotage that authorities have attempted to link to the underground terrorist organization led by the two sons of executed former president Zulfiqar Ali Bhutto.

While no conclusive evidence has surfaced to suggest that the violent incidents are the product of organized subversion, President Mohammed Zia ul-Haq is treating them as such, amid growing public pressure to restore law and order.

Zia last month ordered that firearms licenses be issued to "law-abiding" citizens to counter the terrorist attacks and warned that he would dispense "exemplary" punishment to subversives. His warning was interpreted as including some form of harsh corporal punishment under Islamic law.

Zia also has issued a new martial-law order providing for the death penalty to anybody convicted of destroying government property, acquiring arms or explosives or contributing to lawlessness.

Nearly 1,000 people suspected of being "subversives" have been arrested following the Sept. 13 assassination in Karachi of Zahur Hassan Bhopali, a prominent pro-Zia politician who had been nominated to the hand-picked Federal Advisory Council, which has replaced the elected Pakistan National Assembly.

Bhopali, one of the most active members of the advisory council and a staunch supporter of the martial-law government, was machine-gunned to death in his office in the most recent of the attacks.

The wave of attacks began Aug. 2 when a car bomb exploded outside the VIP lounge at the Lahore airport, injuring eight persons. A British Broadcasting Corp. correspondent later received a telephone call purported to be from the Al-Zulfiqar terrorist group headed by Murtaza and Shahnawaz Bhutto, the former president's sons. The caller said the car-bomb attack was intended to kill three Cabinet ministers who had left on a flight for Karachi 15 minutes earlier.

Later in August, two fires in Lahore damaged a general post office and a Water and Power Development Authority headquarters, and on Sept. 4 a fire broke out in a law office next to the Lahore High Court. Authorities blamed arsonists.

The next day shots were fired at the home of Saeed-ur-Rehman, a justice on the High Court in Lahore. The same week, a small explosive device was thrown at the home of another Federal Advisory Council member, and two other prominent Zia supporters, including Interior Minister Mahmoud Haroon, reported receiving threatening letters.

On Sept. 9, 39 buses owned by the government transport service in Lahore were burned in a fire attributed to arson. There were also two major bank robberies in September, one in Lahore and one in Karachi, which had the appearance of being organized by a guerrilla group.

The significance of the incidents lies not so much in any indications of an organized subversive movement as in the reaction of the government and the possibility that it will tighten martial law as a result.

Rather than minimize the importance of the incidents, Zia and his top aides have gone out of their way to focus attention on what they claim is an organized attempt to create instability in Pakistan and bring down the government.

Last February, however, according to informed diplomatic sources, a shoulder-fired missile was launched at Zia's presidential airplane. The incident that was never reported in the Pakistani press.

The missile was fired as Zia's plane taxied on the runway at Rawalpindi Airport for a flight to Lahore, where Zia was scheduled to dedicate a new factory.

Pakistani officials still decline to discuss the attack. Persistent but unverified rumors have circulated for months about other attempts on Zia's life.

Zia, who has promised repeatedly to hold elections since overthrowing Bhutto in 1977 and dissolving the National Assembly, has used the wave of terrorism to justify postponing the return of democracy, suggesting that the people are not ready for elections and that the military government is protecting an illiterate population from demagoguery.

In a recent speech, the president said the Islamic concept of democracy is "slightly different" from that in Western nations and that "Islam does not believe in the rule of the majority. It would be unacceptable if the majority wanted something that was against Islamic principle, said Zia. He promised last month to announce the outlines of an Islamic democratic system within a year.

In the past, Zia has tempered his public position on democracy, aware that the martial-law government has aroused concern in a U.S. administration that has embarked on a $3.2 billion military sales and economic aid package to shore up Pakistan against the Soviet Union.

But Western diplomats here believe that if a public perception grows of Zia as helpless to stop the violence, the president will respond by tightening martial law, which, when compared to military dictatorships in Latin America and the Middle East, is loosely administered.

"The consensus in Pakistan is to do something to stop the terrorism. Whether or not all these incidents are related is almost irrelevant if he uses them to justify a crackdown," one diplomat said.

Last February the military government cracked down on what it labeled "antisocial elements" and arrested 4,400 persons, about a fourth of them workers in political parties.

Observers here said that if the current wave of violence continues, a similar roundup could follow.

Given Zia's longtime ambition for an Islamic state that outlaws all secular political parties, the most likely target of a new crackdown would be the Pakistan People's Party, which is led by Bhutto's family. Bhutto was hanged in 1979 for alleged crimes against the state.

Although the Pakistan People's Party has sought to distance itself from Al-Zulfiqar because of the group's unpopularity in Pakistan, the Zia government has persistently linked the two, and the likelihood is that a tightening of martial law attributed to Al-Zulfiqar would be blamed by some Pakistanis on the most popular of the old political parties.

"If this violence continues, it is not going to be very comfortable for us," said a Pakistani journalist and Pakistan People's Party supporter who writes for the daily newspaper Amn in Karachi.