Somali pirates have captured a small Saudi tanker and its crew, the EU naval force in the Gulf of Aden says.

The tanker, travelling from Japan to Jeddah, was empty when pirates hijacked the vessel and took its crew captive.

The MT Nisir Al Saudi was outside the shipping lanes patrolled by naval warships, it was reported.

Somali pirate attacks usually increase in the months between March and May because calmer seas allow the pirates to operate more freely.

The captain of the ship is Greek but the nationalities of the rest of the crew are not known.

In November 2008 Somali pirates hijacked the Sirius Star, a Saudi supertanker loaded with two million barrels of oil.

They released it after two months in return for a ransom, believed to have been $3m (£1.95m), which was parachuted on to the deck of the ship by helicopter.

The latest ship to be captured was taken to the Somali town of Garacad, a known pirate stronghold, said Cmdr John Harbour of the EU Naval Force in the area.