Attackers seized 53 vessels worldwide last year - all but four off the coast of Somalia - according to the International Maritime Bureau's piracy reporting center in Kuala Lumpur.
The number of hostages and vessels taken "are the highest we have ever seen" since the center began monitoring attacks in 1991, its director, Pottengal Mukundan, said in a statement. "The continued increase in these numbers is alarming," he said.
The Somali attacks accounted for 1,016 hostages held for ransom, the center said. Somali pirates are currently holding 31 vessels and 713 crew members of various nationalities after hijacking another four ships so far this year, it said.
Somalia's position on the Horn of Africa means pirates can use its long coastline to capture ships. The country has not had a functioning government since a dictatorship collapsed in 1991, and an international flotilla of warships patrolling the waters has struggled to prevent hijackings.
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The naval patrols have foiled many attacks, but pirates are moving farther offshore to boost their success in hijackings, the piracy reporting center said.
"All measures taken at sea to limit the activities of the pirates are undermined because of a lack of responsible authority back in Somalia," it said in its statement.
Overall, there were 445 pirate attacks worldwide last year, a 10 percent rise from 2009, the center said. Eight crew members died - all attributed to Somali pirates.
Violent attacks and armed robberies were also notable in Indonesian waters, where 30 vessels were boarded. Bangladesh had 21 vessels boarded, mainly by attackers armed with knives at the port of Chittagong, while Nigeria had 13, mostly near the port of Lagos.