One night about 10 days ago a retired major general named Tajammal Hussain Malik was talking by phone from his home in Lahore to an old Army buddy, a major in a regiment in the hill town of Murree not far from here.

According to rumors that are circulating through the bazaars and the diplomatic missions here, Milk is supposed to have suggested that his pal help get rid of "the turkey" -- referring to Gen. Mohammed Zia ul-Haq, the president of Pakistan.

The call was tapped by authorities here, according to the rumors, and police soon arrested both Malik and his Army buddy, whose name has not surfaced.

Malik, according to one report, was drinking at the time of the call.

That widely circulated story is believed to have been the source of recent published reports that authorities had broken up an attempted coup against Zia's martial-law government.

Zia gave the government's only real acknowledgment of a possible plot against his rule when Pakistani correspondents asked him today if he could offer a comment on reports of a coup attempt.

"By itself it was nothing. An individual has subjected himself to the mischief of law and we will deal with him according to the law," Zia said.

"It is not deep-rooted," he said. There is nothing more than what is on the surface, but it has been projected in such a manner around the world as if Pakistan had been turned upside down, which is not right.

"I have a very firm conviction that this could not have taken place unless there was a foreign hand involved."

Zia identified neither the individual involved nor the "foreign hand."

While most diplomats here do not believe there was any serious coup plot against the Zia government, many Pakistanis -- who depend largely on rumors and a reading between the lines of the censored press -- are convinced that something was in the works.

The coup reports are more likely to be believed now, after more than 2 1/2 years of martial law and no elections, because of official hints of possible changes in the government.

Zia has contributed to this uncertainty by talking enigmatically of Cabinet changes and hinting at possible shifts among the ruling Army generals.

There is a feeling among many here that Zia has to bring some political figures into his government, especially after canceling promised elections last October.

Diplomats here said this feeling helped make the rumors of a coup more believable among Pakistanis.

Moreover, the fact the rumors are widely believed underscores the fragility of the Zia government and illustrates the common belief here that many of Zia's fellow Army officers feel they could do a better job running Pakistan than he does.

But Zia appears unconcerned about the reports, one of which mentions his deputy Army chief of staff, Lt. Gen. Mohammed Iqbal Khan, as one of the plotters.

As soon as Iqbal's name surfaced in a London Urdu-language newspaper last week, the government announced that he would be taking part in a military ceremony the next day. A picture of him at the ceremony was prominently displayed in the press and on television, but this has not stilled the talk.

Zia also has been seen frequently at public meeings in the past few days, exuding confidence and jousting verbally with reporters about possible government shifts.

The only public notice here of the coup reports was a brief Associated Press of Pakistan story in Friday's papers that Malik is likely to face trial soon for offenses that "are said to be of the type to attract the michef [apparently meaning mischief] of the law. It could not be ascertained if he was acting under outside influence," the story continued.

Malik was retired from the army in 1976 during the rule of Zulfiqar Ali Bhutto, who was overthrown by Zia in 1977 and later executed. Malik originally was a member of Bhutto's Pakistan People's Party but there were reports that he was cashiered from the Army for plotting against Bhutto.

Since leaving the Army he formed a small Moslem fundamentalist political party, but was considered more of a character than a major player on the political scene.

If that Malik report is indeed true, diplomats here believe calling it an attempted coup is an exaggeration. They speculate that it is, rather, a crackdown on grumblers against the government at a time of extreme sensitivity. c

But there have been other rumors circulating here, less widely believed in the diplomatic community but with a following in the bazaar.

According to these reports, there was an actual plot scheduled for March 23, Pakistan's national day and a time when Army promotions and transfers are usually announced. The expected promotions and transfers -- including the possibility that Zia might give up his position as Army chief of staff and the possible retirement or transfer of the four military governors -- have generated unusual speculation and anxiety among military personnel and civilians.

Zia attempted to calm that anxiety today by announcing that he was separating the jobs of governor and Army corps commander for Pakistan's four provinces. The four generals now holding those dual posts will continue as governors and remain in the Army, Zia said, while four newly promoted lieutenant generals will take over the Army corps commands.

Along with the coup rumors, there are widely varying reports of arrests of field-grade Army officers.

One usually well informed Western embassy here has told other diplomats that there was a general roundup of "grumblers" -- officers who were said to be hurting the morale of their units by complaining about the government.