Members of the Sinhala and Tamil communities have clashed again in eastern Sri Lanka after a grenade attack on a bus left one person dead.
Police have imposed a curfew on the town of Trincomalee
Police have imposed a curfew on the town of Trincomalee.
Members of both communities took to the streets after Sinhalas blamed the Tamil Tiger rebels for the attack, which also seriously injured two.
On Saturday, the Tigers threatened to return to war unless peace talks based on their plans for self-rule resumed.
According to Trincomalee police chief, Neville Vijaysundra, almost 2,000 security personnel have spread out around the town and reinforcements are expected.
The BBC's Dumeetha Luthra in the capital, Colombo, says police are hoping to avert large-scale clashes between the Sinhala and Tamil communities.
Tiger leader Velupillai Prabhakaran has threatened a return to war
Sinhala crowds started gathering after a grenade was thrown into a bus carrying passengers from Colombo to Trincomalee.
The Sinhalas started throwing stones at Tamil passers-by, bringing Tamil groups out onto the streets.
Tiger officials in the area denied the group carried out the attack.
During an annual radio broadcast to mark the rebels' war dead on Saturday, Tiger leader Velupillai Prabhakaran said he had "reached the limits of patience" on the peace process.
He said government delays on discussing rebel demands would leave them "no alternative" to the "freedom struggle".
President Chandrika Kumaratunga last week urged the rebels to compromise.
A ceasefire between the two sides has remained largely intact since February 2002, even though the Tigers pulled out of negotiations in April last year, saying the government was not honouring pledges it had made.
The Tigers have been fighting for more than two decades for self-government in the north and east, which they consider the Tamil homeland.
More than 60,000 people have been killed in the course of the conflict.