KUALA LUMPUR, Dec 7 (Reuters) - Ships have been told to keep a lookout to guard against pirate attacks in the South China Sea off eastern Malaysia following an attack on a vessel last week, the International Maritime Bureau said on Sunday.

The warning came after pirates attacked a coal ship 10 nautical miles off the coast of the eastern Malaysian island of Tioman on Monday and robbed the crew.

"There were four attacks in the same location, one of it was the hijacking in the Tioman and we believe it is the same group operating in the area. So we are warning ships to maintain piracy watch," said Noel Choong, regional manager for the bureau's Piracy Reporting Centre in Kuala Lumpur.

He said the caution was for ships off the South East Malaysian island of Tioman in the South China sea and applied for a radius of 100 nautical miles.

In last week's attack pirates in speedboats armed with swords attacked a coal ship sailing from Singapore to Thailand. They did not seize the vessel.

Unlike in war-torn Somalia where piracy in the Gulf of Aden has become a major issue threatening world trade, piracy in the waters around Malaysia and Indonesia is now rare after a crackdown.

The Strait of Malacca between peninsular Malaysia and Sumatra is among the world's busiest shipping lanes, used by more than 70,000 ships in 2007, including vessels supplying about 80 percent of the energy needs of Japan and China.

Piracy in the Strait became so serious that in 2005 the Joint War Committee of the Lloyd's Market Association added the area to its list of war risk zones, sending premiums sharply higher.

Concerted efforts by Malaysia, Indonesia and Singapore helped slash the number of attacks in subsequent years. (Reporting by Varsha Tickoo and David Chance; editing by Matthew Jones)

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