COLOMBO, SRI LANKA, JUNE 3 -- The Sri Lankan Navy turned back a flotilla of 20 boats from India today as it entered the island nation's territorial waters with relief supplies intended for Tamils on strife-plagued Jaffna Peninsula, a government spokesman said. India reacted angrily.

"The Indian boats have turned back," spokesman Tilak Ratnakara said. "We were adamant that they cannot be allowed to come to Jaffna and the boats are going back."

In New Delhi, an External Affairs Ministry spokesman said India "strongly condemns the action by Sri Lankan gunboats in forcibly preventing the convoy of Indian relief vessels, carrying urgently needed and essential items and medicines, from proceeding to Jaffna."

The statement continued, "This action of the government of Sri Lanka in preventing the urgently needed relief supplies from reaching the long-suffering people of Jaffna, coming in the wake of the five-month-long economic blockade and the brutal killing of hundreds of innocent civilians in recent weeks by the Sri Lankan armed forces, makes it clear that the government of Sri Lanka is determined to continue denying the people of Jaffna their basic human rights."

Sri Lankan government sources said several Sri Lankan patrol boats intercepted the 20 fishing boats just inside Sri Lankan waters in Palk Strait, which separates India from the tear-shaped island, formerly called Ceylon.

After an encounter between the commander of the Indian flotilla and the Sri Lankan commander, the Indians anchored off Kachchativu Island, 11 miles from Rameshwaram, the small southern Indian port from which they sailed.

"We asked them to stop and they said they were determined to go through because the people of Jaffna were starving," a Sri Lankan source said. "We said nothing of the kind was happening. They agreed to anchor off Kachchativu and our man asked them to come aboard for a talk. They said they would only come if Red Cross and the media people came with them.

"We said this was not possible," the source said.

After laying at anchor for several hours, the flotilla, carrying food, fuel and medicines, sailed back to India.

India, home of 50 million Tamils, said it sent the supplies because of shortages on the Jaffna Peninsula -- the main stronghold of Tamil separatist guerrillas -- after a Sri Lankan blockade and a military offensive against the rebels.

Colombo denies the 800,000 Jaffna Tamils are suffering food shortages. It says it would accept Indian aid through normal channels as a goodwill gesture but not New Delhi's attempt to ship and distribute the supplies directly, which would infringe its sovereignty and territorial integrity.

Kachchativu Island, where the flotilla anchored, is about 35 miles southwest of Jaffna town, which is controlled by guerrillas of the Liberation Tigers of Tamil Eelam who are fighting for an independent Tamil homeland in northern and eastern Sri Lanka.

According to the sources, the flotilla, which also carried about 100 Indian and foreign journalists, was heading for Kalmunai Point at the tip of a narrow neck of land five miles southeast of the town. Shallow waters make navigation off Jaffna impossible for all but the smallest craft, but fishing vessels might have been able to ferry the supplies from Kalmunai Point.

Each of the Indian boats flew a large Red Cross flag. They sailed from Tamil Nadu, a state in southern India that is home to 50 million Indian Tamils. Eight Indian Red Cross officials as well as Indian External Affairs Ministry officials were accompanying them in a different vessel.

Sri Lanka has denied Indian allegations that several hundred innocent civilians were killed in a security forces offensive launched against rebels at Vadamarachchi on the Jaffna Peninsula last week.

Buddhist monks, opposition parties and local newspapers joined the government today in condemning India's action.

About 30 saffron-robed Buddhist monks gathered outside the Indian embassy in Colombo today to demonstrate against the Indian move and the killing of monks, allegedly by Tamil guerrillas, yesterday. The rebels reportedly stopped a bus and shot dead 30 monks and seven civilians in the eastern district of Ampara. The totals increased with the death today of five injured. One of the dead monks was 12 years old.

A Reuter reporter who visited the Army garrison in Jaffna's old Dutch fort today saw three dead soldiers and 40 wounded, all victims of a four-hour attack on the fort by an estimated 150 rebels last night. Observers believed the attack was a response by the Tigers to last week's offensive, in which the Army wrested the northeast corner of the peninsula from their control.