COLOMBO, Sri Lanka — Authorities imposed a curfew on a restive northeast Sri Lankan town today after angry mobs clashed and set fire to shops following two explosions, officials said. At least 16 people were reportedly killed in the unrest and explosions.

Sri Lankan army and navy units were patrolling the streets in Trincomalee to enforce the curfew and curb the violence that erupted after two explosions rocked the port town killing seven people, including two policemen and a soldier, and wounding two others.

Nobody claimed responsibility for the blasts and it was not immediately known who started the mob violence, which left nine other people dead, according to doctors and the military.

A Tamil legislator said he was told that Sinhalese mobs attacked ethnic Tamils following the second explosion.

"I heard an explosion and thereafter I received several calls saying that mobs are attacking Tamil people and their shops," said Kadirgamathamby Thurairatnasingham, a legislator for Trincomalee.

The majority of Sri Lankans are Sinhalese, but the country's north and parts of the east are dominated by the Tamil minority and partially controlled by the rebels, who began fighting in 1983 for a separate homeland, accusing the Sinhalese of discrimination.

A ceasefire halted the fighting in 2002, but rising violence in recent months has threatened to plunge the country back into civil war.

Top rebel official Seevaratnam Puleedevan said, "we severely condemn the brutal violence on Tamils and it reminds (us) of what happened to the Tamils of this country in 1983," referring to the anti-Tamil riots that spawned the separatist campaign.

The government blamed Tamil Tiger rebels today's explosions but said it planned to attend a second round of peace talks with the Liberation Tigers of Tamil Eelam rebels later this month in Geneva, Switzerland aimed at shoring up the ceasefire.

"We are pursuing peace with all tolerance and commitment, but this should not be taken as our weakness," government spokesman Keheliya Rambukwella told a news conference today. "The government is trying to show its goodwill to sit down and talk with the LTTE."

However, Puleedevan warned that if violence against Tamils continues "it will be extremely difficult for us to participate in (the) talks."

In New York, UN Secretary General Kofi Annan expressed concern over the escalating violence and urged all concerned to continue with the peace process.

"The secretary general appeals to both the government of Sri Lanka and the LTTE to meet in Geneva as planned," UN spokesman Stephane Dujarric said.

European ceasefire monitors warned that violence could spread across Sri Lanka.

"There is a real danger that the violence that erupted today could spread throughout the country resulting in more innocent people dying if the two parties do not act quickly to bring the situation under control," the Sri Lanka Monitoring Mission said in a statement.

The first mine blast today struck a truck carrying policemen, killing at least two officers and wounding two others, said Senior Supt. of Police Nihal Samarakoon.

Later, five people, including one soldier, were killed in the second explosion, said military spokesman Brig. Prasad Samarasinghe. The attacks involved Claymore mines, which the rebels are known to use.

Local journalist Mangalanath Liyanaarachchi said he saw the second blast.

"The blast was a few metres away from me and I saw some people on the ground," said Liyanaarachchi. "Then some boys started to run riot, stopping Tamils and attacking them."

Dr. Vidya Sri Kasipillai said 11 dead bodies were brought to Trincomalee General Hospital where she works, following the second explosion and violence. Another physician at the hospital, who spoke on condition of anonymity, said at least 40 people had been admitted with injuries.

Samarasinghe said an indefinite curfew had been imposed in Trincomalee, about 230 kilometres northeast of the capital, Colombo.