COLOMBO, Sri Lanka, AP -Sri Lanka declared a state of emergency and soldiers searched homes and vehicles for suspects Saturday following the assassination of the nation”s foreign minister, a slaying that put the island”s fragile peace process at risk.

The military blamed the separatist Tamil Tiger rebels for the death of 73-year-old Lakshman Kadirgamar, who was shot in the head and heart late Friday after finishing a swim at his home. Kadirgamar, an ethnic Tamil himself, had led efforts to ban the Tamil rebels as a terrorist organization but later backed peace negotiations.

President Chandrika Kumaratunga declared a state of emergency Saturday and appealed &#34for calm and restraint in the face of this grave and cowardly attack&#34 on Kadirgamar.

A rebel spokesman declined to say if the group was responsible.

&#34I”m waiting for a reaction from our leaders,&#34 Daya Master said by telephone from the rebel-controlled town of Kilinochchi. But, he added, government officials &#34always put the blame on the LTT whenever such things happen.&#34

During a state of emergency, authorities have the power to detain without charge anybody suspected of involvement in terrorist activities, and to search and demolish buildings.

As dawn broke over Colombo, dozens of military trucks moved into the city and soldiers took up positions at major intersections.

The military is checking all vehicles coming in and out of the capital, Brig. Daya Ratnayake said.

Navy patrol boats were also ordered to guard the coastline, some of which is controlled by the Tigers.

Late Friday, elite soldiers and policemen cordoned off the area where the killing occurred, conducting house-to-house searches. Two people were arrested at a nearby house.

Police officer Nimal Lewke said two snipers had hidden in a building near Kadirgamar”s heavily guarded home in Colombo”s diplomatic district, and fired through a ventilation hole in an upper floor.

Police found cheese and chocolates they ate while they waited for their target, along with a grenade launcher intended as a backup weapon.

Ratnayake, who said police last week arrested two Tamil men who were shooting video in the area, blamed the rebels for the killing.

&#34We have reasons to believe that he was killed by the Liberation Tigers of Tamileelam,&#34 Ratnayake said. &#34He was always under threat.&#34

But Justice Minister John Seneviratne was more cautious.

&#34We can”t say as yet who”s behind this, but the minister had been getting threats,&#34 he said.

An Oxford-educated lawyer, Kadirgamar led an international campaign against the Tigers, who remain on terrorist lists in five countries, including the United States and Britain.

A Web site sympathetic to the guerrillas said the slain minister obstructed the rebel cause.

&#34In short Kadirgamar was responsible for our stagnated campaign in the international scene,&#34 the pro-rebel Nitharsanam Web site said.

Rebel attacks against Sri Lankan political leaders were once common. Kumaratunga was gravely wounded in a 1999 assassination attempt. Police blamed Tamil rebels for that attack, which killed 26 people.

Such high-level attacks stopped after a February 2002 cease-fire, but tensions have recently increased between the government and the rebels. There has been a surge of attacks in the volatile eastern region, occasionally spilling into the capital, Colombo.

&#34The situation has deteriorated,&#34 said Hagrup Haukland, chief of a team of European truce monitors. &#34It”s a big, big blow to the cease-fire and the whole peace process irrespective of who is behind this.&#34

He said it was &#34too early to speculate if there was going to be an outbreak of war.&#34

The Tamil Tigers began fighting in 1983 for a separate homeland for ethnic Tamils in the country”s north and east, claiming discrimination by the majority Sinhalese. The conflict killed nearly 65,000 people before the Norway-brokered cease-fire.

Post-truce peace talks have been stalled since 2003 over rebel demands for wide autonomy in this country of 19 million people.

Kadirgamar, a Tamil Christian who was a close aide to Kumaratunga, was appointed foreign minister in April 2004 and also held the position from 1994 to 2001.

Secretary of State Condoleezza Rice denounced the assassination as &#34a vicious act of terror, which the United States strongly condemns.&#34

Rice urged Sri Lankans not to let the assassination lead to a resumption of civil war.

Kadirgamar, always considered a top Tamil rebel assassination target, had strongly supported a negotiated peace settlement.