By Jonathan Kent
BBC News, Kuala Lumpur
The Malacca Straits are notorious for pirate attacks
There has been a sharp rise in the number of people killed at sea by pirates, according to experts.
The International Maritime Bureau's piracy reporting centre in Malaysia says 30 mariners were murdered in 2004 - half of them in waters off Nigeria.
That figure made the year one of the bloodiest since the centre started collecting statistics on piracy 15 years ago.
However, the number of attacks in 2004 actually fell.
There were 325 acts of piracy recorded last year, against 445 reported in 2003.
Indonesia accounted for more than a quarter, with 93 raids in its waters - down from 121 the previous year.
Killed by tsunami
Attacks in the narrow Straits of Malacca, which lie between Malaysia and the Indonesian island of Sumatra, also dropped sharply to 37.
Increased patrols by the Indonesian navy and its Malaysian and Singaporean counterparts may have played a part in reducing the total.
However, four people were killed while passing through the Malacca Straits.
The coasts of Nigeria were the deadliest waters, with 15 seafarers murdered.
At 30, the total number of murders was up by almost a third on the previous year.
The centre also noted that attacks in the Malacca Straits all but ceased in the wake of the Indian Ocean tsunami.
Before the disaster it had been alleged that most of the pirates were from Aceh, with some blaming a spate of kidnappings in the area on Acehnese separatists.
The Piracy Reporting Centre says it believes that many pirates died, and their boats and weapons were destroyed, when the tsunami's waves struck.