Colombo, Sri Lanka ? Sri Lanka imposed a state of emergency Saturday after the sniper assassination of the foreign minister, a killing that officials blamed on the Tamil Tiger rebels and warned could rupture the island’s fragile peace process.

Soldiers scoured the capital for suspects and helicopters and military jets patrolled over rebel-controlled territory, though the government said it had not taken steps to break the cease-fire with the Liberation Tigers of Tamileelam. The group insisted it was not responsible.

Foreign Minister Lakshman Kadirgamar, 73, an ethnic Tamil who led efforts to ban the Tigers as a terrorist organization but later backed peace efforts, was shot in the head and chest late Friday after finishing a swim at his home. He died after midnight.

“It is a grave setback to the peace process,” an official who leads government peace efforts, Jayantha Dhanapala, told reporters.

The Tigers began fighting in 1983 for a separate homeland for ethnic Tamils, claiming discrimination by the majority Sinhalese. The civil war killed nearly 65,000 people in the country of 19 million before a Norwegian-brokered cease-fire in 2002.

Sri Lankans buy the morning papers carrying news of the assassination of Foreign Minister Lakshman Kadirgamar, an outspoken critic of the Tamil Tigers, Saturday in Colombo, Sri Lanka. Sri Lankan President Chandrika Kumaratunga declared a state of emergency Saturday after the assassination.

Subsequent peace talks broke down, however, over rebel demands for greater autonomy in the areas under their control in eastern and northern Sri Lanka.

The rebels’ political chief denied any role in the killing and criticized officials for “hastily blaming” the group.

Sri Lankan officials were skeptical.

“We find it extremely difficult to accept the denial,” government spokesman Nimal Siripala de Silva told reporters. “It’s very, very difficult to accept.”

Still, he said the government would take no action to violate the truce.

The state of emergency declared by President Chandrika Kumaratunga empowered authorities to detain without charge anyone suspected of taking part in terrorist activities and to search and demolish buildings.