Southeast Asia has become the world's hot spot for piracy after an international crackdown slashed the number of hijackings off the coast of war-torn Somalia, the UN says.
That compares with January 2011, when Somali pirates held 736 hostages and 32 boats, some onshore and others on their vessels.
Meanwhile piracy has surged in Southeast Asia, particularly in the maritime trading hub of the Malacca Strait, between Malaysia and Indonesia. Attacks in the region topped 150 last year after starting an upward trend since 2010.
"Piracy in the Malacca Strait continues to be a major disruptor for safe routes in the eastern Indian Ocean," the agency said.
Last month the International Maritime Bureau said that there had been 23 actual or attempted attacks in Southeast Asian waters between January and March, mainly off Indonesia.
The UN agency said piracy was likely to become even worse in the region as the centre of gravity of global shipping continued to shift towards Asia.
"With changing climatic conditions at high latitudes and medium to low-income countries in Asia experiencing the largest growth per capita, additional transport routes may be explored," it said.
Attacks off the Horn of Africa spiralled from the early 2000s, with pirates hijacking cargo ships and taking crews prisoner for months and even years.
Much of the reduction in attacks is down to the international fleet that has been mounting patrols in the Gulf of Aden and Indian Ocean.
The World Bank estimates piracy costs the global economy US$18 billion a year in increased trade costs. That amount "dwarfs the estimated US$53 million average annual ransom paid since 2005", it says.
Another area of focus is the Gulf of Guinea off West Africa, where there were 50 incidents of piracy last year.