Sri Lanka declared a state of emergency Saturday following the assassination of the country's foreign minister.

Lakshman Kadirgamar, 73, was shot in the head and heart after finishing a swim at his heavily-secured home in the capital Colombo late Friday.

Kadirgamar, an ethnic Tamil, had led efforts to ban the rebels as a terrorist organization. But he later backed peace negotiations.

The military blamed the separatist Tamil Tiger rebels for the killing.

But the group's political chief, S.P. Tamilselvan, denied any role in the killing and criticized officials for "hastily blaming" the group.

The government said Saturday that it would not take any action that will violate the ceasefire with the rebels, but said it would take precautions to protect its citizens against terrorist attacks.

Officials said seven people have been detained in connection with the killing, as the Defence Ministry sent soldiers to search homes and vehicles for more suspects.

Dozens of military trucks moved into Colombo Saturday and soldiers have taken up positions at major intersections, checking vehicles coming in and out of the city.

Navy patrol boats were also guarding the coastline, some of which is controlled by the Tamil Tigers.

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

"We have taken the steps" to safeguard our people, said the office of President Chandrika Kumaratunga.

"A state of national emergency has been declared to facilitate enhanced security measures and effective investigations of this wanton act of terror."

The president said Kadirgamar had been killed by "political foes," but she stopped short of accusing the Tamil Tigers.

This wasn't the first time Kadirgamar has been attacked. He was gravely wounded in a 1999 assassination attempt, which police blamed on the Tamil rebels.

His slaying has put the island's fragile peace process at risk, and Kumaratunga has appealed for "calm and restraint in the face of this grave and cowardly attack."

Police officer Nimal Lewke told the Associated Press that two snipers involved in the assassination were hiding in a building near Kadirgamar's home, and that they shot through a ventilation hole in an upper floor.

The ceasefire

Claiming discrimination by the majority Sinhalese, the Tigers began fighting in 1983 for a separate homeland for ethnic Tamils.

Nearly 65,000 people died in the conflict, before a Norwegian-brokered ceasefire in 2002.

Since then, the Tigers have been observing the ceasefire, but tensions have recently increased between the government and the rebels. A surge of attacks in the volatile eastern region have occasionally spilled into Colombo.

"The situation has deteriorated," Hagrup Haukland, chief of a team of European truce monitors, told the Associated Press. "It's a big, big blow to the ceasefire and the whole peace process irrespective of who is behind this."

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

Condemnation

Canada's Foreign Affairs Minister Pierre Pettigrew condemned the assassination in a statement, calling it an unconscionable act committed against a member of the Sri Lankan government.

Pettigrew also said Kadirgamar worked tirelessly for a lasting resolution to Sri Lanka's fragile peace process, and this act should not be allowed to derail those efforts.

U.S. Secretary of State Condoleezza Rice denounced the assassination as "a vicious act of terror which the United States strongly condemns."

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

India on Saturday reiterated its support to the island nation's fight against forces seeking to undermine its unity. A statement released by the Indian foreign ministry called the killing a "terrorist crime."