Sri Lanka's foreign minister, a member of the ethnic Tamil minority who led an international campaign to ban the Tamil Tiger (search) rebels as a terrorist organization, was assassinated after a swim at his home Friday. The military blamed the rebels.

Lakshman Kadirgamar (search), 73, was shot in the head and heart about 11 p.m. and died at National Hospital, hours after he delivered a speech to a group of students on international relations.

"The minister had just returned from a swim and was getting inside his home when he was shot," Inspector General of Police Chandra Fernando said. He said there were two snipers hiding in buildings near Kadirgamar's heavily guarded home in the capital's diplomatic district.

Authorities began house-to-house searches in the area and made two arrests at a neighboring house.

Meanwhile, President Chandrika Kumaratunga's (search) office prepared to declare a state of emergency to "facilitate the investigation process," said her spokesman, Eric Fernando. The emergency law, used at the height of the conflict between the government and the Tamil Tigers, allows authorities to detain without trial anybody suspected of involvement in terrorist activities.

Brig. Daya Ratnayake said that over the past week police had arrested two Tamil men who were taking video of the area.

"We have reasons to believe that he was killed by the Liberation Tigers of Tamileelam," Ratnayake said, using the rebels' formal name. "He was always under threat and had one of the best protections."

The justice minister, John Seneviratne, was more cautious.

"We can't say as yet who's behind this, but the minister had been getting threats," Seneviratne said outside the hospital.

Rebel attacks against Sri Lankan political leaders were once common.

Kumaratunga, who rushed to the hospital after the shooting, was herself gravely wounded in an assassination attempt in 1999. 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 been growing lately between the government and the rebels. There has been a surge of attacks in the volatile eastern region, occasionally spilling into the capital, Colombo.

"The situation has deteriorated," Hagrup Haukland, chief of the cease-fire monitors told The Associated Press. "It's a big, big blow to the cease-fire 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," but added that he had informed monitors stationed in district offices to be on the alert.

Elite policemen and soldiers condoned the area around Kadirgamar's home, and the air force deployed helicopters to search for the assailants. Authorities tightened security at all entry and exit points to the city.

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. Sri Lanka, an island nation about the size of West Virginia, is located less than 20 miles from the southeast coast of India.

Kadirgamar, a Tamil Christian who was a close aide to Kumaratunga, was appointed foreign minister in April 2004 and previously held the position from 1994 to 2001. An Oxford-educated lawyer, he led an international campaign against the Tigers, who remain on terrorist lists in five countries, including the United States and Britain.

The United States denounced the assassination.

"This senseless murder was a vicious act of terror, which the United States strongly condemns," Secretary of State Condoleezza Rice said in a statement. "Those responsible must be brought to justice."

Rice urged Sri Lankans not to let the assassination lead to resumed civil war.

Kadirgamar was the only lawmaker with heavy security even while he was in the opposition, as he was considered a top Tamil rebel target.

However, after the cease-fire Kadirgamar had strongly supported a negotiated settlement to the civil war.

Cooperation between the government and the Tamil rebels extended to an agreement they signed on June 24 to share international relief aid for survivors of the December earthquake and tsunami, which killed more than 31,000 in this country and left tens of thousands homeless.

But scores of people — including security forces, rebels and civilians — have been killed since a senior Tiger leader split from the mainstream group last year with some 6,000 fighters. Each side has blamed the other for the violence.

On Thursday, Anton Balasingham, the London-based chief negotiator for the Tigers, warned that Sri Lanka could slip back into civil war unless the government stops backing armed groups that the rebels claim are attacking them.

Balasingham accused the government of paying and providing logistics support to paramilitary groups, allowing the armed forces to "sustain a shadow war" against the rebels. He called it a grave violation of a 2002 cease-fire agreement between the rebels and the Sri Lankan government.

The government, however, denies providing support to paramilitaries.

Kadirgamar is survived by his wife, Suganthie; and by two children, Ragi and Ajitha, from an earlier marriage.