Pirates seized a Greek-owned Malta-registered cargo ship off the coast of Somalia today, Greece's merchant marine ministry said.

"Pirates seized the Maltese-flagged cargo ship Saldanha, with 22 crew, off Somalia," the ministry said. It said the vessel, loaded with coal, was sailing to Slovenia.

Piracy off Somalia, one of the world's busiest shipping areas, and other coasts of Africa has increased sharply over the past year, earning the pirates millions of dollars of ransom payments and pushing up maritime insurance rates.

In January, pirates seized another Greek vessel off the coast of Cameroon and killed its Greek captain. EU forces foiled a pirate attack on a Greek-flagged crude oil tanker off the coast of Somalia in the same month.

NATO ships began anti-piracy operations off the Somali coast in late October but they have failed to stop a spate of attacks.

In December the European Union took over control of the operation.