The rebel Liberation Tigers of Tamil Eelam (LTTE) said they told Oslo's top envoy here, Hans Brattskar, that Colombo must control the "disruptive elements" responsible for violence in the island's embattled north-east in the past week.

"The ambassador discussed the political situation ... with special reference to violent incidents during the last week... and expressed concern over possible risk to the ceasefire and the peace process," the Tigers said.

The talks came as concern grew that the island could slide back into war and as the northern districts of Vavuniya and Mannar were paralysed following the one-day strike called by front organisations of the LTTE, officials and the defence ministry said.

Violent clashes in the northeastern port district of Trincomalee left two people dead and several wounded, police said, as security was stepped up in the northern regions.

The International Committee of the Red Cross withdrew staff from main entry points into rebel-held territory in the absence of guarantees for the safety of their staff, a spokesman said.

The main A-9 highway that runs through the Tiger-held Wanni region to the northern peninsula of Jaffna was closed Thursday at Vavuniya, 260km north of Colombo, an ICRC spokesman said.

The defence ministry said up to 25,000 people travelling between rebel-held areas and the rest of the island were affected by the work stoppage organised by the LTTE.

"This is an orchestrated move by the LTTE to disrupt normalcy and discredit the security forces," the ministry said in a statement.