Military authorities in Iran's main oil-producing region arrested 20 strike leaders and fired a number of others today as production climbed back to 2.1 million barrels a day, industry sources reported.

The production increases coincided with implementation of strict new measures aimed at ending the country's crippling two-week-old oil workers's trike. It marked a rise of 500,000 barrels over yesterday but still left production at a third of its normal level for this time of year.

The military prime minister, Gen. Gholam Reza Azhari, yesterday ordered martial law authorities in Khuzestan Province to start rounding up "agitators" behind the strike and try them in a military court under the Oil Industry Sabotage Act of 1957.

Sources said the court has been set up in Ahwaz, the administrative center of the Khuzestan oil fields. They said the 20 persons arrested were employed at the Gazhsaran oil fields, one of Iran's largest, where workers are the most militant against the shah. Discharge notices were issued to some workers at the Aghahari fields, but no arrests were made there, sources said.

In Tehran, a former prime minister and close associate of the shah said the embattled monarch is prepared to become a figurehead in an effort to appease opposition to his rule and remain on the throne.

Jaafar Sharif-Emami, who was prime minister for about two months until a military-led government came to power in early Novemberm, said Shah Mohammad Reza Pahlavi is now "convinced that for the health of the country and the benefit of the dynasty, he sould resign and not rule."

Such a civilian Cabinet with the shah remaining as a symbol of the nation alone lines of European monarchies, despite its appeal to those seeking compromise, is not a "realistic" solution to the vast political and economic problems facing Iran and probably would be short-lived, opposition sources said.

The millions who marched in protest demonstrations in Iranian cities a week ago made it clear by their banners and slogans that they want nothing short of the shah's permanent removal, they added.

But loyalists to the shah, such as Sharif-Emami, argue that most Iranians would still accept hima as a figurehead if they were convinced of his good faith. "The people are not thinking normally and will say anything because they are nervous now," he said in an interview.

The shah's decision to relinquish the authoritation powers he has tirelessly built up during his 37-year rule, but which have been slipping away from him hthis year, was made in connection with proposals to form a new civilian government, Sharif-Emami said.

Another former prime minister, Ali Amini, is reported ready to put together a government under a crown or regency council to oversee a transition to free elections. But the country's leading religious and political opposition figures have said they will neither join nor support such a government.

Speaking at his luxurious, roomy villa in North Tehran, Sharif-Emami insisted the shah must remain in the country "because he is the only man who can keep order in the military."

A spokesman for Karin Sanjabi, leader or the oppositio National Front, disagreed, saying "We believe just the opposite."

Sharif-Emami, 68, who previously has been prime minister briefly during a turbulent period 18 years ago, said the idea of substituting a crown council for the shah's rule would be acceptable to the monarch with some "small changes," notably one allowing him to be chairman of the council.

Oppostion sources tended to scoff at the idea. "How can you have the shah as chairman of it?"

Sharif-Emami said under such a scheme, the shah would not have any veto or other extraordinary powers. "He is convinced that his power should be transferred to legal government," the former prime minister said.

A Shite Moslem leader is due to fly to Paris Monday to confer with the exiled religious opposition chief, Ayatollah Ruhollah Khomeini, political sources said. They denied the envoy, Ayatollah Hussein-Ali Montazeri who was released from prison two months ago, would try to mediate a compromise between Khomeini and politicians who favor an independent government under the shah.

"We are not trying to arrange anything between what the shah is demanding and what Khomeini is opposing." a National Front source said. "There is nothing to be negotiated with the government at this stage."

Azhari's new get-touch attitude in the oil fields apparently came after strikers rejected his warnings that public sector employes who refuses to return to work face dismissal. The strikers reportedly offered to resume some operations, but produce only enough oil to meet domestic consumption.

According to industry sources, Azhari told the Khuzestan governor-general that only full production was acceptable and ordered him to appoint two generals to take charge of the Gazhsaram and Aghajari fields and a third for the Ahwaz and Marun fields, which provide the bulk of Iran's crude Production.

The general flew to the fields by helicopteer yesterday afternoon and told company officials they had instructions to begin arresting strike leaders. The sources cautioned that even if everyone immediately returns to work. It will take at least another 10 days to build up to full production again.

The picture is further clouded by a general strike call for Monday from opposition forces. Exiled Shite Moslem leader Ayatollah Ruhollah Khomeini has ordered his followers to continue their strike, particularly in the oil industry, until the shah is forced from his throne.