The Tamil Tiger rebels claimed Friday that Sri Lanka's navy encroached on their sovereign rights by approaching coastal areas they control, and warned they will attack any vessels threatening their homeland.

Mahendrarasa Gajendran, 17, a suspected Tamil Tiger supporter who was shot by unknown gunmen, is treated at a hospital in the eastern City of Trincomalee, Sri Lanka, Friday, May 12, 2006. More than 150 people have died in violence since the beginning of April, and recent attempts to restart stalled peace talks have failed and pushed the country slipping back to civil war. [AP]

The Liberation Tigers of Tamil Eelam, or LTTE, also warned European cease-fire monitors not to board navy vessels off the coast of rebel-controlled areas in the north and east.

The warnings came a day after Tamil Tiger rebels sank a navy patrol boat in a northern Sri Lanka sea battle in that left about 50 insurgents and 17 sailors dead or missing, in a sharp escalation of violence that pushed the country closer to all-out war.

"We entered the peace process based on a status quo achieved in the battlefield in our territory," the chief of the Tamil Tiger rebels' political wing, S. P. Thamilselvan, said after meeting Friday with the head of the European cease-fire monitors, Ulf Henricsson, in the rebel stronghold of Kilinochchi.

"Nobody has the right to pass judgment on the sovereign rights of our access to the adjacent sea and air space of our homeland," Thamilselvan was quoted as saying by the pro-rebel TamilNet Web site.

In a letter Friday to the cease-fire monitors, the rebels accused the navy of disturbing civilian and LTTE activities, and warned they could retaliate.

Accusing the navy of using the cease-fire monitors as "human shields," the rebels issued a stark warning to the monitors.

"We urge you for the last time not to be on board Sri Lankan naval vessels until further notice from us. If you chose to ignore our warning and request, we are not responsible for the consequences."

The government and the monitors have accused the Tigers of violating Sri Lanka's 2002 cease-fire accord in Thursday's attack.

Government troops retaliated, sinking five rebel boats, damaging three others and launching airstrikes on guerrilla-held territory.

Fifteen sailors and two officers were on board the downed navy boat.

"Hopes are receding," navy spokesman Commander D.K.P. Dassanayake said Friday of any of the 17 missing. The navy had yet to locate the wreck.

At least 50 Tiger guerrillas were on five rebels boats that sank, and all were believed dead, Dassanayake said.

No independent verification of the casualty toll was immediately available.

More than 150 people have died in violence since the beginning of April, and recent attempts to restart stalled peace talks have failed.

The Tigers began fighting in 1983 to create a separate state for ethnic minority Tamils, accusing the majority Sinhalese of discrimination. More than 65,000 people died in the conflict before the 2002 truce.