By Ranga Sirilal

COLOMBO, May 30 (Reuters) Tamil Tiger rebels killed four soldiers in Sri Lanka today, the military said, while the Red Cross resumed operations in the north a week after pulling back over safety concerns.

The killings in the northwest district of Mannar, where the Tigers control a swathe of territory, came after President Mahinda Rajapaksa had suggested setting up a peace zone in the area, which is home to the popular Madhu Catholic church.

''There was a confrontation near Madhu. The army lost four soldiers and one was injured,'' said military spokesman Brigadier Prasad Samarasinghe, adding two rebels were also believed killed.

The Tigers were not immediately available for comment.

Fighting is now focused on the north after the military captured the Tigers' eastern stronghold, and today's clash is the latest in a string of land and sea battles in recent months. Around 4,000 people have been killed since last year alone.

The International Committee of the Red Cross said it would send staff back to checkpoints that sit on defence lines separating government from rebel-held territory in Mannar and the northern district of Vavuniya.

The Red Cross pulled its staff out a week ago after gunfire and mortar bomb incidents.

''The ICRC has decided that its personnel will resume their presence ... for three days a week,'' it said in a statement.

''In discussions with the Sri Lankan government and the Liberation Tigers of Tamil Eelam (LTTE) over recent incidents jeopardising the safety of civilians and ICRC personnel, the ICRC obtained the security guarantees it needed to resume its tasks.'' The government has vowed to destroy the Tigers militarily, while the rebels say they will step up attacks using a homegrown air force of light planes smuggled into the country in pieces in their fight for an independent state.

Analysts say there is no clear winner on the horizon and fear a protracted conflict that has killed nearly 70,000 people since 1983 could rumble on for years.

REUTERS GL HT1618