A bomb exploded on a civilian bus in the central Sri Lankan town of Dambulla on Saturday, killing at least 20 people and wounding 50, the military said.
The explosion was the latest in a series of bomb attacks blamed on the Liberation Tigers of Tamil Eelan (LTTE), the rebel group fighting to create an independent state in the island's north and east.
"The death toll has gone up to 20 and are 50 injured from the explosion," said military spokesman Brigadier Udaya Nanayakkara. "The explosion is a work of the LTTE."
The military said the victims were travelling north from the central town of Kandy to Anuradhapura to attend a religious ceremony.
Dambulla is around 150 km (90 miles) north of the capital Colombo.
Local television showed footage of the aftermath of the explosion. The bus's roof was partly blown off, windows were shattered and the vehicle's steel frame bent and torn.
Many of the injured were taken to hospital by civilian vehicle.
The attack came as Sri Lanka was preparing to celebrate on Monday its 60th year of independence from Britain, and the military had stepped up security over concerns of attacks.
Saturday's blast occurred at a bus station and came about three weeks after a roadside bomb ripped through a civilian bus killing 27 people and wounding dozens in the central town of Buttala.
On January 16 a six-year ceasefire between the government and Tamil Tiger rebels officially expired.
The Tigers were not immediately available for comment.
Clashes between the rebels and government troops have escalated since the truce was scrapped last month. The two-decade conflict has killed an estimated 70,000 people. (Reuters)
Bus bombing kills 20 in Sri Lanka