COLOMBO, SRI LANKA, OCT. 13 -- Advancing Indian troops tightened their hold around the Tamil stronghold of Jaffna but met heavy resistance from entrenched rebels as casualties mounted on both sides, Indian Embassy spokeswoman Lakshmi Puri said today.

Puri said 27 Indian soldiers have been killed and 141 wounded in four days of fighting in northern and eastern Sri Lanka to suppress guerrillas of the Liberation Tigers of Tamil Eelam.

She told a news briefing in the Sri Lankan capital that about 200 rebels have been killed and 270 captured.

There was no independent confirmation of the situation in Jaffna, which has been closed to journalists.

{In the first non-Indian account of fighting in and around Jaffna, local witnesses spoke of at least 160 civilian deaths and many hundreds of wounded, the Manchester Guardian reported from Colombo.

{Their claim came in a brief telephone call from the beleaguered town to a western embassy in Colombo. Before the call was cut off, two men, described by diplomats as regular contacts and reliable informants, one of them having Red Cross connections, said there had been almost constant shelling from Indian positions since Sunday.

{The callers also spoke of attacks from the air by "bombers" and helicopter gunships. In Jaffna, they said, at least 100 people had died. They said they had heard of 60 more deaths outside the city.}

India has sent more than 12,000 troops to the island at the request of the Sri Lankan government to enforce an Indian-Sri Lankan peace pact signed on July 29 to end a four-year Tamil separatist revolt.

Indian troops, supported by tanks and heavy artillery, pushed steadily from the north, east and west toward the center of Jaffna, the island's third largest city, Puri said, as rebels put up a desperate resistance in street-by-street battles.

She would not say when Indian troops are expected to reach the city center. A senior Sri Lankan officer said, "It could be at any moment or in the next few days."

Puri said guerrillas prevented civilians from fleeing to safety and used them as "human shields" to mask operations, a charge also made yesterday by the state-run All India Radio.

The rebels said in a statement issued in Vavuniya, about 100 miles south of Jaffna, that in fighting at Jaffna University yesterday, guerrillas captured one Indian soldier and recovered the bodies of 40. It said rebels were prevented from handing over the bodies to Indian forces, "so we burned them."

The statement said two Indian helicopters and a plane bombed and strafed the university grounds, killing 28 civilians and wounding 72.

Puri said aircraft were being used only to ferry troops and supplies. She said the heaviest weapons used by the Indians are 120-mm mortars and that tanks and armored personnel carriers are used only "in direct firing roles to neutralize {rebel} positions."

Residents of Chavakachcheri, 10 miles east of Jaffna, told reporters that they heard explosions and gunfire through the night. Some said many civilians had been killed or wounded.

Indian forces began their offensive Saturday to end a rampage by the rebels, who had killed more than 200 Sinhalese.

Joint Indian and Sri Lankan naval patrols have been increased in the Palk Strait between the countries to isolate the Jaffna rebels.

Military sources said the rebels appealed by radio to comrades in Madras, southern India, to rush arms and reinforcements to Jaffna.

Sri Lankan state radio said that most of Jaffna city's 150,000 residents had sought refuge in a Hindu temple and Delft Island in the west.

In Batticaloa, two land-mine explosions were reported yesterday and today, and Puri said one Indian soldier was killed and four wounded.