Attacks near China and in the South China Sea also featured prominently, with Asia accounting for nearly half the worldwide total.

There were seven in the triangle, 17 in Indonesia, two in the South China Sea and two near China.

'This is a continuing area of concern for the safety of ships sailing between Japan and Southeast Asia,' the report said.

'The total number of incidents recorded from January 1 to May 31 indicates a large increase as compared to the same period for the previous year.

'These attacks were often of a serious nature and in seven incidents firearms were used. Two crew members of the victim vessels received bullet wounds and some vessels were hijacked.' Publication of the report coincided with an announcement by China that it had arrested nine men accused of robbing ships in the Pearl River Estuary.

Some were not mainlanders, an official of the provincial Shipping Public Security Bureau said.

The men were accused of boarding and robbing ships at anchor overnight. There had been 20 such reports since February.

'This is just one group of nine pirates. There are certainly others still operating,' the official said.

Shipping in the South China Sea and in the waters off south China, Vietnam and Cambodia has long been plagued by pirate bands ranging from small local groups to larger organised gangs.

However, a source said none of the 20 reports had been received by international organisations, and suggested it could be a case of China appearing to clamp down on piracy in light of the Hye Mieko incident.

In June, the freighter, carrying US$2 million (HK$15.6 million) worth of cigarettes and photographic equipment, was reported by its owner to have been seized by pirates in international waters and taken to Shanwei in Guangdong.

Chinese officials have said the Panamanian-registered 1,055 gross tonne Hye Mieko was in custody on suspicion of smuggling and declined to comment on reports from its owner that the vessel was hijacked by what appeared to be the crew of a Chinese patrol boat.

The Singapore shipowner, William Tay, had travelled to Shanwei in a second attempt at talking Chinese authorities into handing over his hijacked ship, the owner's colleague said yesterday.

Mr Tay would try to convince the Chinese to release his ship, along with her cargo and 14 Burmese and Indonesian crewmen, the colleague said.

Mr Tay denies the smuggling charges and says the Chinese military hijacked his ship.

He went to Shanwei and tried for eight days to negotiate with Chinese authorities for the release of his ship, crew and cargo, but without success.