The International Maritime Bureau (IMB) recorded 174 attacks on the high seas in the first nine months of 2006, compared to 205 in the same period last year. Six crew were killed and 20 were kidnapped, while 113 ships were boarded.

"The reduction in attacks is welcome. Credit for this must go to the law enforcement agencies responding to the attacks in high-risk areas," it said in a statement.

However, the IMB said there were 33 incidents in Bangladesh, mostly near the main port of Chittagong, "resulting in it being accorded the title of the world's most dangerous port".

"Attempts have been made to deal with the problem in Bangladesh, notably a recent joint coast guard and navy operation to capture pirates in the Bay of Bengal," it said.

The IMB said the operation involved 17 naval vessels and 3,000 coast guard personnel who sought to clear pirate-infested areas of the bay and stop pirates using them to shelter from the authorities.

The maritime watchdog also singled out Nigeria, and said attacks there had been particularly violent, often with the use of guns and knives and involving large groups of pirates, including 40 in one attack on a vessel.

"The pirate attacks are symptomatic of a large rise in the number of incidents against foreign oil workers in the country generally, something that has gained wide international media attention recently, and where local politics are now having a direct impact on the safety of shipping in the area," it said.

Elsewhere the situation had improved, and the IMB noted the Malacca Strait -- which runs between Indonesia and Malaysia and down to Singapore -- was dropped from Lloyd's list of dangerous waterways.