A bus packed with about 70 civilians was hit by a claymore mine attack somewhere in north-central Sri Lanka on Wednesday night. The explosion led to the killing of at least 15 passengers and to the wounding of 40 other, sources from the local police said.

The unfortunate accident occurred in Abimanapuram in Kebithigollewa, 220 kilometers north-east of Sri Lankan capital, Colombo. The hospitals located in the region have been put on standby to receive any casualties. A similar bus bombing in the area in June 2006 killed 64 passengers, AFP said.

According to the government officials, the Tamil Tiger rebels are responsible for the explosion, though they did not claim it. No other details are immediately available.

Just a few hours earlier, the Sri Lankan military announced that its forces had killed about 29 Tamil rebels in the fighting carried out in the north of the country, which began Tuesday in the districts of Mannar and Vavuniya. Eleven soldiers were also killed on Wednesday in separate accidents or fire exchanges throughout the country.

This incident follows the decision of the Sri Lankan government to set free about 1,000 people of the 2,500 that were detained after a security sweep in the capital, Colombo, after 18 people were killed in the city because of two bombs.

Over 5,000 people died since 2006, when the fighting between the rebels and the military resumed.

The conflict between the Sri Lankan forces and the LTTE - Liberation Tigers of Tamil Eelam - has started 24 years ago and over this period there were more than 70,000 people killed in the clashes. Two attempts of reaching peace were made, but after the last of them made during the peace-talks held in Geneva a year ago, the fighting has intensified.