Land mines blasts in northern Sri Lanka killed four soldiers and two Tamil Tiger rebels on Monday, raising the death toll from a week of bloody unrest to at least 50, police said.

The violence is some of the worse since a 2002 cease-fire that continues to be challenged by clashes between ethnic Tamils and the majority Sinhalese.

The soldiers were killed by a remote-controlled land mine in government-controlled Vavuniya, said police chief Gamini Silva. The town is 130 miles north of the capital, Colombo.

"Right now what we know is that four soldiers are dead and seven are wounded," Deputy Inspector General of Police Gamini Silva said.

In rebel-held Jaffna, north of Vavuniya, a similar device exploded during transport, killing two rebels, local police said.

Discrimination against the Tamils led the Tigers to take up arms in 1983, and a resulting war with government forces on this tropical island of 19 million left more than 65,000 people dead before Norway brokered the cease-fire.

On Sunday the rebels said they would not attend peace talks with the Sri Lankan government in Switzerland unless they can hold an internal meeting first.

Rebel commanders on Saturday canceled a trip to the internal meeting, saying they felt threatened by the presence of naval ships. The government said the four craft were there to ensure the rebels' safety.

The talks in Geneva have been scheduled for April 24-25.

Sri Lanka's Sinhalese majority is made up mainly of Buddhists and accounts for about 14 million people. They dominate the military and police.

The Hindu Tamils, in contrast, number about 3.2 million, and are concentrated in the country's north and east and in the tea-growing hills of central Sri Lanka.