More than 35,000 trapped Tamil civilians on Monday made a dramatic breakout from the LTTE-controlled areas in Sri Lanka's embattled north with President Mahinda Rajapaksa handing out a last 24-hour deadline for Tiger Supremo V Prabhakaran and his top aides to surrender.

Proclaiming that the mass exodus indicated a "complete defeat" of Tigers was imminent, Rajapaksa warned after this his forces would make an "all out" bid to wrest the last 20 sq kilometers area from the Tiger control on the northern coast.

As the breakout was unfolding two suicide bomb attacks suspected to be LTTE handiwork were reported in the no fire zone in which 17 people were feared killed.

Displaying aerial video footage of masses of trapped civilians making a beeline for freedom shot by Sri Lankan spy planes flying overhead, the President said the exodus has come as his forces made a significant breakthrough by capturing LTTE defence fortification bunds outside the no-fire zone.

"The video footage clearly shows that the people are defying the rebels and are escaping. They are running for safety," Rajapaksa said.

The President went to the Air Force Headquarters to watch the visuals of Tamil civilians making a breakout for freedom.

Elaborating on the ultimatum, a Defence spokesman told said that the ultimatum had begun at 1200 hrs local time.