Investigators hunting for the masterminds behind three co-ordinated suicide bombings on the island of Bali circulated photographs of the bombers' severed heads in Indonesian newspapers today, hoping for a quick identification.

Police also sought three accomplices believed to still be on the Indonesian resort island, and enlisted a former operative of South-East Asia’s top terror group to help track down the plotters of Saturday’s attack, which killed 19 people and injured about 100.

Officials released a list of 25 people still unaccounted for after the bombings - including one British citizen, 12 Indonesians, two Americans, two Japanese and two Danish.

But Catherine Philp, South Asia Correspondent of The Times, said from Bali that that did not necessarily mean that the Briton was among those killed because the number of those missing exceeded the number of unidentified bodies. "No one can rule it out so far," she said.

The suspects in the near-simultaneous bombings on three crowded restaurants were believed to have used explosive belts - loaded with ball bearings to maximize the damage - that blew apart their torsos. But their heads were intact, swollen and bruised but remarkably well-preserved, said Major-General Ansyaad Mbai, a top anti-terrorist official.

That - and a chilling video capturing a suspected bomber strolling past diners at one of the cafes moments before it was blown up - could provide a tremendous boost to the investigation.

Major-General Mbai said results could come within days, adding that police think at least three other people were involved in the attacks and probably were still at large on Bali

"If the past is any precedent, they have planned safe houses and lying low, letting the first dragnet pass over head," said Ken Conboy, a Jakarta-based security consultant.

Nobody has claimed responsibility for the attacks at two seafood cafes on Jimbaran beach and a noodle-and-steak house in the bustling tourist center of Kuta, three miles away, all packed with diners on the busiest night of the week.

But suspicion immediately fell on Jemaah Islamiyah (JI), whose members were convicted for attacks on two crowded nightclubs on Bali three years ago that killed 202 people, and two other deadly terrorist attacks in Jakarta in 2003 and 2004.

South-East Asian intelligence officials have repeatedly warned that the group could be orchestrating a major terrorist attack in the region and, fearing more strikes in the days ahead, were clamping down.

Thailand, which draws millions of sun-seeking tourists every year, put all of its major resort areas on full alert today after Thaksin Shinawatra, the Prime Minister, gave warning that terrorists "are commuting and rotating around in the region". The Philippines and Australia were also on heightened alert.

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