The United States, Japan, the European Union and Norway asked the government and the rebel Liberation Tigers of Tamil Eelam (LTTE) to build confidence by implementing what was agreed last week.

The quartet known as the co-chairs presided over efforts in June 2003 to raise international support for the island's Norwegian-backed peace initiative.

"The co-chairs stress the importance of the parties implementing these commitments on the ground so as to build confidence and a conducive environment for progressing towards lasting peace for all peoples of Sri Lanka," they said in a statement.

Peace broker Norway managed to get the two parties to talk in Switzerland to save their truce. It came under renewed pressure following a surge in violence that killed at least 153 people between December and January.

Colombo initially insisted on rewriting the February 2002 truce arranged by Norway. But after the Tigers resisted the move and threatened to walk out, Colombo backed down and agreed to uphold the ceasefire.

Colombo has also agreed to ensure that other militant groups will not be allowed to operate, especially in the island's restive east where the Tigers face attacks from a breakaway faction.

More than 60,000 people have been killed in the ethnic conflict in the past three decades and four previous peace attempts have ended in failure.

Both sides have agreed to stop the killings, at least till their next round of talks in April.