COLOMBO, Sri Lanka - Facing imminent battlefield defeat, Sri Lanka's Tamil Tiger rebels declared a unilateral ceasefire Sunday and called on the government to halt its offensive to spare the tens of thousands of civilians trapped by the fighting.
The government rejected the appeal and accused the rebels of playing for time as the military stands poised to rout them and end the separatist war that has plagued this Indian Ocean island nation for a quarter century.
"This is a joke," Defense Secretary Gotabhaya Rajapaksa said of the rebels' truce offer.
The ceasefire declaration came amid a chorus of international appeals for a pause in the fighting to allow the estimated 50,000 ethnic Tamil civilians remaining in the war zone to escape. The government and aid groups accuse the rebels of holding the civilians hostage to blunt the government offensive, a charge the rebels deny.
Reports from the region have detailed growing cases of starvation and civilian casualties in recent days.
The United Nations, which says nearly 6,500 civilians have been killed over the past three months, has sent its top humanitarian official on an emergency mission to Sri Lanka to push for a ceasefire. John Holmes met Sunday with senior government officials to underscore "the urgent need for humanitarian access by the UN to the combat zone," UN spokesman Gordon Weiss said.
The government barred aid workers from the region when the fighting escalated in September.
Holmes was to head Monday to the northern region of Vavuniya to inspect displacement camps and hospitals that have been overwhelmed by the more than 100,000 civilians who fled the war zone over the past week.
British Foreign Secretary David Miliband will also visit Sri Lanka with his French and Swedish counterparts on Wednesday to try to mediate on the conflict, according to a statement from the prime minister's office in London.
In response to the international truce appeals, the rebels said Sunday that all offensive military operations would "cease with immediate effect."
They asked the international community to pressure the government to halt its offensive as well, saying the "humanitarian crisis can only be overcome by the declaration of an immediate ceasefire," according to a statement e-mailed to The Associated Press.
Both sides have declared previous ceasefires during the recent fighting, but they did little more than briefly disrupt the war's momentum because the other side continued fighting.
The Tamil Tigers, listed as a terrorist group by many Western nations, have been fighting since 1983 for an ethnic Tamil state in the north and east after decades of marginalization by governments dominated by the Sinhalese majority.
The rebels ran a shadow state across a vast swath of the north. But a government offensive forced them out of their strongholds in recent months, cornering them into a narrow coastal strip six kilometres long.
New fighting erupted Sunday in the shrinking war zone, with navy patrol boats attacking a squad of rebel craft in a two-hour battle, destroying three boats and killing at least 12 insurgents, the military said.
Army troops also seized the rebel-held village of Valayarmadam after gunbattles, said military spokesman Brig. Udaya Nanayakkara.
In a sign rebel morale was crumbling, 23 insurgents dressed as civilians surrendered to the advancing troops, Nanayakkara said. Many rebel fighters wear glass vials filled with cyanide around their necks and are under orders to commit suicide rather than allow themselves to be captured.
Last week, two prominent rebels -- the group's former media spokesman, Velayutham Dayanithi, known as Daya Master, and an interpreter for its political wing, known only as George -- also surrendered.
Despite international concern, the offensive is wildly popular with many Sinhalese.
President Mahinda Rajapaksa's coalition won a sweeping victory Sunday in a local election seen as a referendum on the war. The government won nearly two-thirds of the vote in the Western Province poll and even secured a majority in the capital, Colombo, long a stronghold of the opposition United National Party, which advocated talks with the rebels.
The governing coalition now controls all eight of the country's provincial councils.
"The electorate ... clearly responded to the call of the president for a united Sri Lanka," Media Minister Anura Yapa said.
