Pirates seized a Greek cargo ship with 22-member crew off the coast of Somalia on Sunday, Greece's merchant marine ministry said.
The Saldanha cargo ship was sailing under the Maltese flag, the ministry said.
According to the UN, Somali pirates carried out at least 120 attacks on ships in 2008, and received ransoms totaling around $150 million for the ships they seized.
Around 20 warships from the navies of at least 10 countries, including Russia, are involved in anti-piracy operations off Somalia. The East African country, ravaged by years of civil war, has no functioning government.