Reuters has reported that pirates have attacked three ships, including two U.N.-chartered vessels and a Japanese bulk carrier, in Indonesian waters around the Malacca Strait in recent days, maritime and police officials said on Wednesday.
Two attacks occurred on ships carrying relief material to tsunami-stricken Aceh province at the weekend, while a Japanese bulk carrier was targeted, reports said.
In at least one of the weekend attacks, raiders were armed with AK-47 rifles, grenades and pistols.
The Japanese vessel, which was 26,989 tons in size, was attacked but its crew fended off the attackers with fire hoses, officials said.
The attacks took to six the total number of piracy incidents in the Malacca Strait this year.