Iran resumed exporting oil today for the first time since the strike 10 weeks ago of oil workers that helped bring down the government of the shah.

With chairman Hassan Nazih of the government's National Iranian Oil Co. looking on, workers began filling the 245-000-ton Japanese tanker World Ambassador at the main export terminal on Kharg Island.

Sirens went off at Iran's biggest refinery here and aboard many of the ships that have been lining up for weeks at this southern port.

In the middle of a knot of workers and reporters, Nazih presented the beaming, bowing Japanese tanker captain and his chief engineer with a framed picture of Ayatollah Ruhollah Khomeini, Iran's revolutionary leader.

But despite the celebration of an event crucial to the new government's survival, uncertainty remained about the future of Iran's oil industry and the critically needed flow of oil revenues.

Nazih said Iran would be exporting about 7 million barrels of crude oil this week and that the country would probably settle down in the future to exporting between 2 and 3 million barrels a day. He said the price on the present sales was about $20 a barrel, well above levels fixed by the Organization of Petroleum Exporting Countries.

But Nazih, a lawyer with no previous experience with the oil industry, offered few clear ideas of where the Iranian oil industry was going. At a later meeting with the press another member of his party, Deputy Chairman Mohammed Ali Marvegh, answered questions.

Marvegh emphasized that Iran was hoping to get away from spot market sales, usually at higher prices but in limited quantities, and back to long-term sales agreements. "We don't like spot sales with no regularity of listing and production. We prefer long-term agreements with good and reliable customers," he said.

Senior officials said the first consignments of crude oil destined for the United States, amounting to about 2 million barrels, would be supplied to Ashland Oil this week. Another customer with whom a spot sale contract has just been signed is Royal Dutch Shell, a member of the Western consortium that has dominated Iran's oil industry for the last quarter of a century and now seems doomed to be broken up.

The company apparently still has received no clear instructions from the government on how much oil it should be trying to produce and export.

The lack of a firm policy at this stage may reflect serious doubts about the level of support the government can expect from oil field workers.

On arrival at Kharg Island, Nazih was greeted by cheers from oil workers and was pushed almost at a trot into the mosque where he was due to speak. He took care to inform oil workers that the first$500 million in oil revenues would be devoted to the welfare of oil industry employes. Nonetheless, he still faced some sharp questioning about work conditions and the fate of those fired, usually as alleged leftists, under the previous government.

News services reported these related developments :

Several more oil-producing countries announced price increases, taking advantage of the shortage resulting from the lengthy cutoff of Iranian exports. Libya announced a second increase of 3 percent on top of a 5 percent increase 10 days ago. It has been joined by Oman and Algeria. Iraq said it would call for a "voluntary premium," on deliveries. Countries announcing increases earlier include Venezuela, Kuwait, Abu Dhabi, Qatar and Saudi Arabia.

Tehran Radio announced the execution of a police officer in Abadan, in addition to the earlier announced death by firing squad of seven former officials after one of the ayatollah's special courts found them guilty of killing or torturing opponents of the shah.

In Bern, the government turned down a request by Iran that Switzerland "freeze" any assets of the deposed shah.

Swiss Justic Minister Kurt Furgler said the Bern government felt that no emergency legislation was needed to resolve the problems raised in an Iranian message of Feb. 16 and suggested that Iran's revolutionary authorities resort to ordinary legal channels to seek repatriation of funds.

The Swiss National Bank announced the results of an inquiry into Iranian holdings in Swiss banks, casting doubt on claims that the shah and his followers sent $21 billion abroad, much of it to Switzerland. It said holdings of Iranian residents, corporate bodies and the Iranian Central Bank totaled $1.170 billion at the end of 1978 in the 25 most active Swiss banks.

This compared with $1.240 billion June 30, before the anti-shah movement gained momentum in Iran.

Kurdish resistance leader Mustafa Barzani, who died in Washington Friday at 76, was buried today in the mountains of northwestern Iran. Thousands of Kurds gathered at the northwestern border town of Oshnovieh for the funeral.

In Armadabad, the secular wing of the Iranian revolution massed a million people in a display of resistance to the country's now exclusively Islamic course. Prime Minister Mehdi Bazargan, moderates, liberals, nationalists and leftist urban guerrilla groups all took part in a rally making the 12th anniversary of the death -- under house arrest -- of anti-shah nationalist premier Mohammed Mossadegh.