Tamil Tiger rebels destroyed a naval patrol craft off Sri Lanka's [Images] northwestern coast on Wednesday, killing five sailors and wounding three others. They also fired mortar bombs at military positions in the troubled northeast, leaving a soldier dead and six people injured.

A flotilla of boats from the Liberation Tigers of Tamil Eelam attacked the naval craft as it patrolled the Kalpitiya lagoon together with another craft, military officials said.

The defence ministry said that the navy, too, had sunk two rebel crafts and at least six guerrillas were believed to have been killed.

"One patrol craft caught fire and the navy requested Air Force support to beat back the attack," a military official said.

The navy and the Tamil Tigers clashed in the same area earlier this month in a major sea battle, which killed more than 50 people.

In another incident, one soldier was killed and six people, including three civilians, injured when Tigers mortared military positions in the restive northeastern district of Trincomalee early on Wednesday, prompting the military to launch retaliatory mortar attacks against the rebel positions, according to the Defence Ministry.

Meanwhile, panic gripped the Sri Lankan capital after threats of bomb attacks against schools in the city. The threats came ahead of the funeral of top amy general Parami Kulatunga, who was killed in a suicide bomb attack on Monday. 

Parents rushed to get back their children home after anonymous callers warned of bomb attacks, officials said. The sharp drop in attendance forced the closure of several schools while in the main provincial capitals there was similar panic, they said.

Police said army bomb disposal sqads were rushed to several schools, but the bomb threats turned out to be hoaxes. An investigation was underway to trace the anonymous callers.

Amid escalating violence, peace broker Norway is expected to meet other truce monitors in Oslo tomorrow to decide the future role of ceasefire observers in the island nation. LTTE rebels last week demanded the removal of observers from European Union members Finland, Sweden and Denmark after the EU outlawed the Tamil Tigers.