Piracy at sea reached record levels in the first quarter of 2003, with more than 100 incidents reported for the first time in a decade.
There were 103 pirate attacks in the first quarter of the year, up from 87 in the same period last year.
The International Maritime Bureau, which compiles the statistics, warned that Indonesia was by far the greatest piracy risk. The country had more incidents than the next three countries combined.
But the IMB praised India and China for handing down long prison sentences to pirates.
India in February sentenced 14 Indonesian pirates to seven years in prison with hard labour, while China the same month sentenced a group of Indonesian pirates to terms of up to 15 years.
"Both the Indian and Chinese authorities should be congratulated for having taken these difficult cases through to prosecution," the director of the IMB, Captain Pottengal Mukundan, said.
"In contrast, the Indonesian authorities recently sentenced the hijackers of Inabukwa [a ship seized in March 2001] to between two and four years imprisonment," he said.
Areas of concern
Indonesia: Anambas Islands, Gelasa Straits
Bangladesh: Chittaging, Mongla
India: Chennai, Chochin, Haldia
Malaysia: Bintulu, Sandakan
Somalia: Red Sea
Indonesia reported 28 incidents of piracy in the first quarter of the year. The next three worst-affected countries - Bangladesh, India and Nigeria - had nine each.
The IMB said Indonesia's Anambas Islands and Gelasa Straits were areas of special concern.
Captain Mukundan did credit Jakarta's move to introduce new patrols of dangerous areas, which did bring down the number of incidents.
The IMB also addressed the problem of terrorism, noting that countries such as Japan have reportedly increased security of oil shipments in connection with the war in Iraq.
Malaysia - where the IMB's Piracy Reporting Centre is based - has taken similar action.
A French oil tanker was attacked by a boat filled with explosives in the Yemeni port of Aden in October of last year.
One crew member was killed and 90,000 barrels of oil were spilled into the Gulf of Aden.