Colombo, Sri Lanka ? Sri Lankan security forces arrested 12 minority Tamils during overnight raids in connection with the assassination of the island’s foreign minister, and a Tamil lawmaker said only a peace deal could stop such killings in a country many fear is sliding back to war.

Defense Ministry spokesman Brig. Daya Ratnayake said Sunday the arrests were made by police and soldiers deployed to search the capital, Colombo, for suspects. The 11 Tamil men and one woman were “being interrogated, but at this moment of time we don’t want to say anything,” he said.

A state of emergency went into effect within hours of Foreign Minister Lakshman Kadirgamar’s slaying late Friday. Top Sri Lankan officials warned that the killing was a major setback to the fragile peace process – and cast doubt on the rebel Tamil Tiger’s insistence that they were not behind the attack.

Ratnayake said a three-year-old cease-fire with the rebels was holding.

“From our side there is no change. We are honoring the cease-fire,” he said.

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.

But subsequent peace talks broke down over rebel demands for greater autonomy.

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 and died after midnight.