(AFP) Business is booming in this tropical paradise a year after six bandits armed with M-16s and rocket launchers stormed ashore to shatter its idyllic existence.

The five diving resort operators on the island off the Borneo coast report near-capacity bookings. One Sabah state official boasts that the security issue no longer exists.

But hundreds of heavily-armed troops and police, backed up by planes, helicopters and dozens of patrol boats, are still on high alert around Sipadan and surrounding islands.

And for some of the Malaysians snatched on April 23 last year - Easter Sunday - the nightmares are still hard to shake off.

Abu Sayyaf bandits seized 21 people - nine Malaysians, two Filipinos working locally and 10 foreign tourists - and sped back by boat to the southern Philippine island of Jolo.

It was the start of a months-long ordeal, which ended in most cases with the payment of hefty sums in ransom as the self-styled freedom fighters disclosed their true motive.

All but one of the Sipadan captives - Filipino Roland Ullah - were eventually freed.

Second kidnapping

In September last year the Abu Sayyaf struck again. This time nearby Pandanan island was their target and three Malaysians were whisked away by speedboat. They were rescued by the Philippine army, which was stung into launching an all-out attack on the bandits.

For some of the Malaysians seized on Sipadan, memories are not a problem.

"I don't fear being back here," said Ken Fong Yin Ken, 28, a divemaster at Pulau Sipadan Resort.

"The security at Sipadan and this area in general has been tightened. The divers are coming in droves as usual and working is a pleasure, as before."

In the Sabah state capital Kota Kinabalu, Wildlife Department ranger Baln Krishnan Nair has a different story.

"I am no longer afraid now ... but for now I don't think I would like to be posted back to Sipadan," he said.

"The first two months (after my release) were not too good. Each time I heard pop sounds, like firecrackers or a car backfiring, I would recall the shooting and bombings we had to endure in Jolo," said Nair, a father of three.

"I have had nightmares about the shootings and I break out in a cold sweat ... the first two months back home were bad. But things are back to normal now."

Nightmares

Vincent Kwong still works as a part-time cook on Sipadan.

"I have put the kidnapping behind me and am relishing my freedom. But at times the nightmares still come back to haunt me. I guess with time I should get over this thing."

For Joy Acune, a 32-year-old mother of two toddlers, life has been less kind. Her husband Roland Ullah, an odd job worker with Borneo Divers, is the only one of the Sipadan hostages still in captivity.

"I have not heard from Roland since the last of the Malaysians were released in August," she said when interviewed in Semporna, the nearest town to Sipadan on the Borneo mainland.

"I keep praying and I know he is safe."

Sabah Tourist Association president Clement Lee said there had been a tremendous increase in US group bookings this year.

The island got a boost when it tied for the title of "Top Dive Destination" in an international survey.

Lee said the security issue no longer existed.

The US State Department does not agree, warning Americans recently to exercise "extreme caution" when visiting the islands off southeast Sabah.

The Malaysian government took exception to the advisory but is clearly still taking security very seriously.

Security forces on watch

At least 550 troops are stationed on 16 islands off Semporna plus five battalions of paramilitary police deployed on 23 islands and 36 coastal posts, equipped with 44 assault boats.

Some 30 police boats plus 29 navy patrol boats are also stationed around the east coast. Navy commandos are in nearby Tawau and air force and police helicopters are also on watch.

Deputy Superintendent Arifin Ibrahim, the Semporna district police chief, said there had been no security breaches since last September although scores of would-be illegal immigrants had been intercepted.

"People, particularly those living on the islands, are our listening posts passing information to security forces. All information is acted on. Nothing is taken lightly," he said.

Local officials say strong defences have restored visitor confidence.

Sabah chief minister Chong Kah Kiat said security will continue as long as necessary. Meanwhile, an aggressive tourism promotion seems to be paying off.

"We have full bookings this month," says one Sipadan resort operator.