NEW DELHI, OCT. 14 -- Indian peace-keeping forces pressed their offensive toward the center of Sri Lanka's northern city of Jaffna today in bitter fighting with Tamil guerrillas that has left a death toll in the hundreds, according to reports here and from the Sri Lankan capital of Colombo.

More than 30 Indian soldiers have been killed and more than 200 wounded, the highest casualties suffered by the Indian Army since the 1971 war that led to the creation of Bangladesh. Tamil rebel casualties have been put at 250 dead.

As the troops advanced to within one to five miles of the city center, Indian officials in New Delhi rejected a call for a cease-fire by the leader of the main Tamil guerrilla group, the Liberation Tigers of Tamil Eelam. India demanded that the Tamil Tigers, as the guerrillas are called, lay down their arms and accept a peace accord signed between India and Sri Lanka in July.

The accord was aimed at ending almost four years of bitter conflict between Sri Lanka's minority Tamils and majority Sinhalese. The violence has left thousands dead.

At the request of the Sri Lankan government, India has sent about 15,000 troops to its island neighbor to enforce the accord.

The full-scale combat between the Indian Army and the Tamil Tigers is a surprising turn of events, since it is widely believed that the guerrillas have used southern India for safe haven and possibly as a source of arms and equipment.

Some analysts expressed fears that prolonged fighting could lead to new pressures on India to abandon its role as enforcer of the peace accord.

"The situation has to break one way or the other in the next few days," one well-informed analyst in Colombo said by telephone. "For India to succeed, it has to be a short, sharp police action."

There is also fear that reports of heavy civilian casualties among the Tamils of the northern Jaffna Peninsula will revive strong sentiments among Tamils living in southern India, leading to an unraveling of the peace accord.

Special protection was ordered today for political figures in the southern Indian state of Tamil Nadu. The leader of the opposition party there was reported to be preparing a campaign critical of the Indian Army role in Sri Lanka.

Indian casualties are reported to include at least one colonel and four or five captains and other officers, indicating an active role by the officers. "They are out there in front leading their troops," said one military analyst in New Delhi.

There are no estimates of civilian casualties but with the heavy fighting, civilian losses are expected to be high.

Casualty figures could not be independently confirmed because India has barred journalists from entering the war zone.

A spokesman for the Indian High Commission, or embassy, said today in Colombo that the operation could have been over in 72 hours except for concern over civilian casualties. The spokesman said large numbers of people had moved out of their homes and into temple areas in response to Indian Army appeals. Relief supplies were reported to be reaching the Jaffna area, but their distribution was said to be hampered by the fighting and heavy rains.

Under the July agreement, the Tamils won semi-autonomy in the Northern and Eastern provinces of Sri Lanka, although the east can choose to stay out of the agreement.

Almost all major Tamil groups accepted the accord except the Tamil Tigers. The Tigers briefly indicated their agreement about two weeks ago, but that was suddenly followed by new demands and a series of violent attacks on other Tamils and Sinhalese civilians. It was the attacks on the Sinhalese last week that apparently triggered India's decision to adopt a hard-line approach to the militant guerrillas.

India apparently hoped that the presence of thousands of troops, backed by tanks and artillery, would be enough to persuade the Tigers to surrender their weapons. Only last week, Indian officials were saying heavy weapons had been turned in and that the Tigers were "finished" as a guerrilla force. Within days of that statement, however, Indian spokesmen were reporting heavy guerrilla resistance to advancing Indian forces.

Tiger leader Vellupillai Prabhakaran, in a letter released in the southern Indian city of Madras, has called on Indian Prime Minister Rajiv Gandhi to end the military operation and resume negotiations with the Tigers "to bring about peace, normalcy and ethnic harmony."

Today, in a stinging response, the Indian government said Prabhakaran had "every chance for two and a half months to negotiate sincerely." Instead, the government statement said, the guerrilla leader "only used this period to prevaricate, to carry on false propaganda and to whip up mass hysteria against India, the Indian peace-keeping force and the Indo-Sri Lankan accord."

The statement said Prabhakaran must ensure that the rebel group "surrenders all its arms, accept the terms of the agreement and declare his full support of the agreement."

The death toll in the current fighting is expected to rise sharply if Indian troops, estimated at between 8,000 to 9,000, are successful in entering the heart of Jaffna and battle the estimated 2,500 armed guerrillas.. The population of the metropolitan area is believed to be more than 500,000.

The guerrillas have an advantage because they are familiar with the twisting streets and narrow lanes of the city. In the past, the Sri Lankan Army always had been reluctant to move into Jaffna because of fear of civilian casualties and support among city residents for the guerrillas.