An opposition boycott of the parliamentary election called by Gen. Mohammed Zia ul-Haq appeared to have crumbled tonight as large numbers of voters turned out for the first national elective balloting since Zia seized power in a military coup more than seven years ago.

Incomplete returns from Pakistan's four provinces indicated that Zia, who extended his presidency five more years on the basis of a controversial referendum in December, would meet or exceed the 40 percent voter turnout minimum he set for himself in establishing a "new political order." Rival parties are not vying for the 207-seat National Assembly.

Leaders of the 11-party opposition alliance, the Movement for the Restoration of Democracy, had predicted a turnout of as low as 10 percent of Pakistan's 35 million registered voters because of their call to boycott what they termed a "sham" election designed to perpetuate Zia's military rule.

Unofficial returns from the most populous areas pointed to a victory for Zia, in that voter participation was at least as strong as it was in the 1970 and 1977 elections -- the only others held since Pakistan was created 37 years ago with the partition of the Indian Subcontinent. Turnouts in those elections averaged about 45 percent.

As he emerged from a Rawalpindi voting booth this morning, Zia told reporters, "The opposition threat has turned into a spent cartridge."

Since political parties were banned from participating in today's election and the 1,291 candidates were required to run as independents, the total voter turnout was the only measurement available immediately to determine Zia's strength against the opposition -- which has called for a lifting of martial law and restoration of the suspended 1973 constitution.

However, in some key races, candidates who are Cabinet ministers or members of the largely powerless Maglis Shoora consultive assembly -- generally considered supporters of Zia -- appeared to be heading toward upset defeats. Some winners were newcomers.

Among those trailing opponents was Information Minister Raja Zaraful Huk, who was contesting a retired air commodore, and Defense Minister Ali Hamed Talpur, who was running behind a provincial minister in Sind.

Voter participation was strongest in the rural areas, particularly in the dominant Punjab Province, which has enjoyed a degree of economic prosperity under Zia's rule, and in regions where powerful landlords and tribal leaders were able to organize backing for candidates.

Balloting was also heavy in urban districts such as in Lahore, the capital of the Punjab, where well-financed candidates organized transportation to get voters to the polls. Some opposition leaders, who had forecast an embarrassingly low turnout that would undermine Zia's standing in his own major constituencies of the military and the fundamentalist religious groups, tonight continued to insist that when final returns were counted in the more remote provinces total participation would be about 25 percent.

"In some rural areas, there was a big turnout. In areas where transportation was provided by candidates, there was participation. But I have the same feeling that it is not exceeding 25 percent," Parvez Hassan, a Lahore attorney and leader of the Tehrik-e-Istiqlal party, said tonight.

However, Mushed Sayed, editor the daily Muslim, which within the confines of martial-law censorship has been persistently critical of Zia's government, said, "I think they pulled it off."

Sayed, who said he had expected a 25 percent turnout, estimated at least 40 percent participation. He also said he believed that the government had been "generally neutral" and that tampering with ballot boxes had been minimal.

For the most part, the election was low-key and short of flashes of violence that often accompany balloting on the Subcontinent. This was partly because of severe limitations on campaigning.

Four persons were reported killed in scattered shootings and four government buses were burned in Lahore city this morning when Movement for the Restoration of Democracy activists attempted to rally. But compared to other Pakistani elections and the more than 40 persons who died in the Indian parliamentary election in December, today's balloting was relatively peaceful.

But voting, like the campaign, was strangely unanimated and colorless -- "like a silent movie," one Pakistani observer in Lahore noted -- with no outward display of enthusiasm by the participants and no sense that national issues were being determined.

"In 1977, you went out and felt the election. You breathed it in the air. This time, it was sanitized," said one opposition activist in Lahore.

At a polling station at the Medina colony in rural Punjab, several dozen government railway employes stood silently in line waiting to mark one of eight candidate symbols on a paper ballot. But there was little evidence of intense political activity.

Many polling places outside Lahore, and in Rawalpindi, near here, were nearly deserted during peak hours, although election commission officials claimed to have recorded large turnouts. Some booths, however, had long lines of voters.

Opposition leaders said that because many of the candidates are essentially political unknowns with no wide power bases, the National Assembly will inevitably become pliable under Zia's broad powers.

Pakistani political analysts here said they expect Zia to strengthen the presidency with even broader powers, including the right to dismiss the prime minister and disband the assembly, and create a National Security Council that could impose emergency rule.

Zia has indicated that eventually he intends to lift martial law, but he has not said when.