Sri Lanka has extended a state of emergency by one month as the government seeks to eliminate the remnants of the Tamil rebel force.

The extension, decided on Tuesday, came with the support of 103 votes from the country's 225-seat parliament.

While the main opposition boycotted the voting, members of the minority Tamil National Alliance, who have 11 seats in the parliament, voted against the extension.

The emergency gives the military and police wide-ranging powers to arrest rebel suspects and detain them indefinitely.

Keheliya Rambukwella, Sri Lanka's defence spokesman, said the emergency powers were still needed to ward off fighters from the Liberation Tigers of Tamil Eelam (LTTE) who could still present a threat.

The government declared on May 18 that its forces had crushed the rebel group, killing Velupillai Prabhakaran, the LTTE leader, and many of his commanders, ending decades of civil war.

The Tamil Tigers began fighting in 1983 for a separate homeland for Sri Lanka's minority Tamil population.

"Although the ground level war is over, there are remnants of terrorism," Rambukwella said.

Emergency rule in Sri Lanka has been in place intermittently for most of the past 30 years.