Colombo: A wave of pitched battles, bombings and an airstrike killed at least 23 people across northern Sri Lanka, the military said on Monday, as a Japanese envoy met with officials to try to stop the raging civil war.

In one attack, a roadside bomb hit a van in the Vavuniya region, just south of the front lines separating government forces from the Tamil Tiger rebels' de facto state in the north, military spokesman Brigadier Udaya Nanayakkara said.

The passengers - civilian workers with a military escort - were returning from an army base after collecting explosives for use in civilian metal mining, he said.

The civilian driver and two soldiers were killed, while three other soldiers and a civilian were injured, the military said. The explosives inside the van did not detonate, Nanayakkara said.

Marginalisation

The rebels have been fighting since 1983 for an independent state for Sri Lanka's ethnic Tamil minority after decades of marginalisation by successive governments, dominated by the Sinhalese majority. The fighting has killed more than 70,000 people.

Violence has surged since January 3, when the government announced its withdrawal from a 2002 ceasefire that had largely broken down amid two years of renewed fighting. At least 319 people have been killed - 301 rebels, 13 troops and five civilians - in that time, according to military figures.

In hopes of reviving the shattered peace process, Japanese mediator Yasushi Akashi met with Foreign Minister Rohitha Bogollagama yesterday as part of a three-day visit to the Indian Ocean island nation.