Malaysia and Thailand have for the first time joined a major US-led exercise in the Pacific Ocean in which some 20,000 personnel are practicing how to coordinate in a crisis, an officer said on Friday.

Billed as the world's largest international maritime war games, the biennial Rim of the Pacific Exercise, or RIMPAC, opened Wednesday for a six-week run off Hawaii.

Colombia, France, Malaysia and Thailand are all new participants in RIMPAC, according to the US Third Fleet, which coordinates the maneuvers.

"By having these nations participate for the first time, they're exposed to how we operate," said US Navy Captain Paul McKeon, RIMPAC's exercise control officer.

"This will allow these new participants to be able to very quickly become part of a multinational organization in the event of a short-notice, real-world crisis event, whether it's hostilities or if it's a natural or man-made event," he told AFP by telephone.

The other participants, which have previously taken part in the games, are Australia, Canada, Chile, Indonesia, Japan, the Netherlands, Peru, Singapore and South Korea.

Three other countries - Brazil, India and New Zealand - are observers in RIMPAC, which has been held since 1971.

A total of more than 150 aircraft, 34 ships and five submarines are taking part in the exercise, according to the US military.

M'sia-US ties improving

Thailand is one of the most longstanding allies of the United States and this year was the host of the Asia-focused "Cobra Gold" exercises.

Malaysia's relations with the United States have been improving since President Barack Obama took office. Malaysia announced this month that it would also join Cobra Gold.

McKeon said that RIMPAC included exercises in counter-piracy, a major concern in the strategic Strait of Malacca.

But McKeon said the exercises were planned without specific consideration to current events such as tensions on the Korean peninsula.

French President Nicolas Sarkozy has building ties with the United States. Last year, France rejoined NATO military command from which it pulled out in 1966.

Colombia is a major recipient of US military support as it fights leftist guerrillas and drug traffickers.

- AFP