Key Points:

Amid driving monsoon rain, a bitter and bloody battle is being fought for one of the Tamil Tigers' last strongholds - a battle that could mark a decisive turning point in Sri Lanka's 25-year-old civil war.

Government troops, buoyed by their recent capture of the western coast of the island, have been pressing to take control of the northern town of Kilinochchi. The town has been the Tigers' de facto headquarters and they are fighting desperately to hold on to it as scores of troops on both sides have reportedly been killed.

Sri Lanka's President, Mahinda Rajapaksa, elected three years ago, has been adamant in his determination to destroy the Tigers.

Reports suggest the man who pulled out of a long-failing ceasefire agreement in January is likely to cement his political power by calling an early election. Analysts say such a move would protect him from criticism over the country's badly stumbling economy.

Brigadier Udaya Nanayakkara, a military spokesman, said: "Heavy fighting is going on in three locations. The rain has started, but it will not affect the troops."

He said Government troops were about 5km north-west of the town and barely 2km to the southwest.

"Soldiers are trying to negotiate the earth [wall] south of Kilinochchi, and are probing the defences," he said.

Yet other reports suggest the Government may be losing higher than expected numbers of soldiers, both through fighting and desertion. An amnesty for deserters has recently been announced by the Government.

The Tamil Tigers have been fighting for an independent homeland for ethnic Tamils since 1983.

They say that since Sri Lanka's independence from Britain in 1948, Tamils have been routinely discriminated against by the Buddhist Sinhalese majority.

The civil war, which has seen human rights abuses committed by both sides, has claimed at least 70,000 lives. The three-front push on Kilinochchi follows the Government's capture two weeks ago of the northern town of Pooneryn, a strategic location held by the Tigers since 1993.

Troops are also said to be attacking the Tiger-held towns of Paranthan and the eastern coast stronghold of Mullaittivu.

Amnesty International said up to 300,000 people were trapped by the fighting and the Tigers were even using civilians as a buffer against the encroaching troops.

Meanwhile, Human Rights Watch said pro-government militias operating in the "liberated" east of Sri Lanka were responsible for a wave of killings and child abductions.

It said the TMVP, made up of former Tigers who switched sides and which emerged as the dominant political force after the Tigers fled the east last year, were responsible for at least 30 murders and 30 kidnappings in September and October.