COLOMBO (AFP) -- Sri Lankan troops and Tiger rebels exchanged artillery fire across a de facto front line in the northern peninsula of Jaffna, leaving at least four soldiers dead, the military said Monday.

The rebel Liberation Tigers of Tamil Eelam (LTTE) fired artillery and mortar bombs at the military defense lines at Muhamalai in the peninsula on Sunday, the Defense Ministry said in a statement.

It said four soldiers were killed while another four escaped with injuries. The military retaliated causing "heavy damages" to the guerrillas, the statement said.

For their part, the Tigers said army troopers had tried to enter their area near Muhamalai and the guerrillas attacked and killed five soldiers.

The pro-rebel tamilnet.com website said the military had intensified artillery and rocket attacks towards Tiger positions in the peninsula.

The latest clashes came as the Tigers Sunday accused Sri Lankan troops of bracing for a fresh offensive in Jaffna and asked Scandinavian truce monitors to step in and check the frontlines.

The area saw heavy fighting in August, which monitors said the Tigers initiated. After two weeks, the military regained territory lost to the rebels following intense fighting that claimed hundreds of lives of both sides.

The Tiger charge also followed heavy fighting in the east of the island where hundreds of civilians fled to neighboring areas for safety.

Both the government and the Tigers have accused each other of triggering the latest fighting which is seen by diplomats as a major setback to reviving peace talks.

The latest flare-up came after Norway's peace envoy, Jon Hanssen-Bauer, left the island after failing to seal an agreement on a site to resume peace negotiations between the two sides.

The government and the rebels did, however, agree on October 28 as the date for opening talks.

Officials said Norway's ambassador here, Hans Brattskar, was due to travel to the rebel-held town of Kilinochchi this week to try to secure agreement on a venue.

Sri Lanka wants talks to be held in Switzerland while the guerrillas want them in Oslo. Allies of the island's ruling party oppose Oslo, charging that Norway is biased in favor of the guerrillas.

Peace negotiations aimed at ending three decades of ethnic bloodshed came to a halt in April 2003 when the Tigers pulled out.