Burmese President Sein Lwin, who took power 17 days ago, resigned Friday after bloody fighting between soldiers and demonstrators that diplomats said left about 1,000 people dead.

The official Radio Rangoon, in a two-paragraph statement, said Sein Lwin requested and received permission from the central committee of the Burmese Socialist Path party - Burma's only legal party - to resign from the posts of president, head of the ruling party and as a member of parliament.Diplomats have said they believe about 1,000 people were killed by army troops used by Sein Lwin to suppress the protests, which erupted Monday in the Southeast Asian nation. Diplomats also said thousands more were injured or imprisoned. The official death toll in the violence, however, was set at nearly 90 people.

The protesters had demanded Sein Lwin's ouster, the establishment of a multiparty system, release of political prisoners and a government that respects civil rights.

An extraordinary party congress is to be called for next Friday, the radio said.

At least 20 people were killed Thursday as troops battled more than 10,000 anti-government protesters who braved gunfire to trap security forces and torch government buildings in the fourth straight day of demonstrations to oust Sein Lwin, who took power July 26.

"People think it's going to get even more violent now," one diplomat, contacted by telephone from Bangkok, said before Sein Lwin's resignation was announced.

Diplomats said there were reports that demonstrators, with the acquiesence of the military, had taken over the civilian administration of Pegu, a city 60 miles north of Rangoon, and in Victoria Point on the southernmost tip of Burma. Rangoon Radio, however, denied the reports about Victoria Point, called Kawthaung in Burmese.

There were also persistent, unconfirmed reports of soldiers refusing to follow orders and of troops joining the demonstrations.

Military Chief of Staff Saw Maung charged that the demonstrators had been infiltrated by "unscrupulous covert saboteurs" who had incited the violence. Saw Maung admitted "the situation is unstable" but blamed the unrest on the demonstrators.

Numerous witnesses and diplomats, however, said the demonstrations that began Monday were peaceful and well-disciplined until the army started firing on protesters late Monday night.

The demonstrations were sparked by serious inflation, shortages of essential goods, and government repression. The last straw was the appointment of the reputedly brutal Sein Lwin to replace Gen. Ne Win, who retired after 26 years of rule over the once-wealthy country of nearly 40 million people.

Students initially led the demonstrations. Sein Lwin, 64, was held responsible by demonstrators for brutal suppression of student demonstrations in March and June as well as his predecessor's earlier crackdown on dissidents.

Official Rangoon Radio said troops opened fire in 18 areas of the city Thursday, killing 15 people and wounding 82. Five other people were killed by the demonstrators, it said - two in Rangoon and three soldiers beaten to death in the city of Sittwe, 320 miles northwest of Rangoon. The reports brought the official death toll to nearly 90 in four days of violence.

But a senior Western diplomat said the government was deliberately concealing casualties. He said embassies in Rangoon estimated that about 1,000 people have been killed throughout the country since Monday.

A diplomat contacted Friday in Rangoon said a unit of soldiers - possibly numbering about 100 - was still believed trapped in North Okkalapa, where some of the worst violence has occurred.