JAFFNA, SRI LANKA, AUG. 4 -- The commander of the main Tamil guerrilla group that has been fighting the Sri Lankan military for the past four years announced today that his men would surrender their weapons to the Indian Army.

Before more than 100,000 followers gathered on the grounds of a Hindu temple here, Velupillai Prabhararan, leader of the Liberation Tigers of Tamil Eelam, said his guerrilla crusade for a separate homeland -- Eelam -- for Sri Lanka's 2 million Tamils had been blocked by the arrival of Indian troops in the Tamil stronghold on the northern tip of Sri Lanka.

"We are going to hand over our weapons to the Indians," Prabhakaran announced, looking sad and defeated as the huge crowd trilled its approval.

"We have no choice but to toe the line of the Indian government," he added. "If we don't, there will be an armed confrontation with the Indian Army. We don't want that. India is a powerful country and we are unable to do anything to stop it."

Watching from VIP chairs in the front rows of the massive crowd, senior Indian military officers smiled when the announcement was translated to them by Tamil interpreters.

A brigade of Indian soldiers came to Sri Lanka last week at the invitation of Sri Lankan President Junius R. Jayewardene after he and Indian Prime Minister Rajiv Gandhi signed an agreement of cooperation to end the bloody ethnic war, in which more than 5,000 people have died.

A key obstacle to the accord had been the refusal of Tamil rebels to accept the provision in the accord that called for them to surrender their arms.

{Military and diplomatic sources said 1,000 Indian reinforcement troops yesterday joined 3,000 Indian soldiers already in Sri Lanka to supervise the surrender, Reuter reported from the Sri Lankan capital, Colombo.}

Now it appears that the Indian Army, not the guerrilla units of the Tamil Tigers, as they are known, are the peace-keepers and heroes of the Jaffna Peninsula. The loudest applause during Prabhakaran's speech came when he announced that the Indian Army would be in charge of Tamil security.

"Rajiv Gandhi has given us assurances," Prabhakaran said. "On the basis of those assurances we have decided to hand over our arms. It does not mean we have given up our dream for Eelam. We are only shifting the responsibility of protecting the people to the Indian Army."

Prabhakaran did not say when the surrender of weapons, estimated by military experts at more than 10,000 pieces ranging from homemade pistols to antiaircraft guns, would take place.

However, the Sri Lankan military commander in chief, Gen. Cyril Ranatunga, said in an interview today that the arms surrender would begin some time Wednesday.

A few Tamil Tigers in the crowd, including one man with a .357 magnum pistol strapped to his hip, confided privately that they intended to keep at least some of their weapons in reserve.

However, they all agreed that the time for fighting was over, at least temporarily.

"We have lost so many men," said one Tiger named Raheem. "So many civilians have been killed. The war is over for now. The struggle will continue on a political level."

Indeed, Prabhakaran, 33, who has been a guerrilla fighter in the separatist cause since he was a teen-ager, said his Liberation Tigers organization may participate in elections for a new majority Tamil province to be created under the agreement signed by Gandhi and Jayewardene. Contrary to rumor, however, he said he would not seek political office himself.

After Prabhakaran concluded his short speech, a phalanx of Tamil Tiger guerrillas formed around him. The young Tamils, most in their late teens and armed with AK47 and M16 rifles, escorted the leader to a waiting black van.