A ransom for the release of cargo ship MV Filitsa has been sent to Somali pirates, according to agencies' reports on Monday.

The reports said the agreed ransom was airdropped by helicopters onto the cargo vessel held by the pirates, but the ship had not been freed immediately.

Armed Somali pirates hijacked the Greek-owned ship with crew members last November in the attacks along the world's most dangerous waters.

Andrew Mwangura, the coordinator of the East Africa Seafarers Assistance Program (SAP), had said the Marshall Islands-registered MV Filitsa was captured about 513 miles off north of Seychelles with three Greeks and 19 Filipinos on board.

The Horn of Africa nation's coastline is considered one of the world's most dangerous stretches of water because of piracy. Somalia is at the entrance to the Gulf of Aden, which leads to the Red Sea and the Suez Canal, one of the world's most important shipping channels.

The country has been plagued by factional fighting between warlords and has not had a functioning central administration since the 1991 ouster of former ruler Mohammed Siad Barre.