The government today launched a search and rescue operation for five sailors kidnapped by pirates in the Malacca Straits and deployed patrol craft and a helicopter to guard against new attacks, a senior official said.

"We have five ships and a police helicopter combing the northern tip of the Malacca Straits," marine police force commander Abdul Rahman Ahmad told AFP .

Malaysia had also asked Indonesia to assist in the search, he said.

Three of the seamen, two Japanese and a Filipino, were kidnapped by a gang of 14 armed pirates from a Japanese-registered tugboat in the strait on Monday.

They are 56-year-old captain Nobuo Inoue, 50-year-old chief engineer Shunji Kuroda and a Filipino crewman whose identity was not given.

Two others, a captain and chief engineer believed to be Indonesians, were abducted after 35 pirates armed with machine guns and rocket launchers seized their fully laden Indonesian registered gas tanker in the strait on Saturday.

Japan said Tuesday it was doing its utmost to secure the release of the kidnap victims. The foreign ministry has set up a task force to handle the crisis and asked Malaysia, Indonesia and Singapore for help, said Foreign Minister Nobutaka Machimura.

Japan's coast guard said it would consider dispatching patrol vessels and aircraft to the area if Malaysia asked for help.

No foreign gunboats

But Abdul Rahman said Malaysia would stand by its policy of not allowing foreign gunboats except those from Indonesia and Singapore to patrol the Malacca Straits.

"Our policy is not to allow foreign ships," he said.

The tugboat with its 11 remaining crewmen and the construction barge it was towing with 154 workers on board were being escorted to Malaysia's Penang island by marine police, Abdul Rahman said.

The strait, one of the busiest waterways in the world, is notorious for pirate raids and concern has been expressed that ships are also vulnerable to terrorist attack.

The owners of the Indonesian tanker MT Tri Samudra have suggested the pirates were rebels from the Free Aceh Movement (GAM), which has been fighting for independence for Aceh province in the north of Sumatra island.

But Abdul Rahman said he believed "there is no political motive in the attacks. Judging from the past, they seek ransom payment for the release of their captives".

He said the pirates could have escaped into Indonesian territory and sought shelter on one of its many remote islands.

On high alert

Noel Choong, head of the Piracy Reporting Centre of the International Maritime Bureau told AFP that seafarers in the strait have been advised to be on high alert and urged Malaysia and Indonesia to increase patrols.

The narrow 960-kilometre strait, bordered by Malaysia, Singapore and Indonesia, is used by about 50,000 ships a year carrying a third of world trade and half its oil supplies.

The three nations last year began coordinated patrols in the strait after Japan and Western countries expressed concern that terrorists could hijack a tanker to use as a floating bomb or to block the vital channel and disrupt world trade.