The European Union is to expand its naval anti-piracy mission to include for the first time Somali "coastal territory and internal waters".

The operation, which started in 2008, will be extended until at least the end of 2014, said EU foreign ministers meeting in Brussels.

A statement said Somalia's transitional government has accepted the EU's offer for greater collaboration in the operation.

Pirate attacks on international merchant shipping in the Indian Ocean and Red Sea have been in steady decline in the past 12 months.

The EU keeps 5-10 warships off the Horn of Africa in an operation known as Atalanta.

Nato has a similar anti-piracy flotilla known as Ocean Shield, and other countries have dispatched naval vessels to patrol the region.

"Today's decision will enable Operation Atalanta Forces to work directly with the transitional federal government and other Somali entities to support their fight against piracy in the coastal areas," said the EU.

The EU did not provide details about the areas that are now open to its anti-piracy mission for the first time, but the long coastline of war-ravaged Somalia provides a perfect haven for pirate gangs preying on shipping off the East African coast.

Although the ministers did not specify what they meant by "coastal territory and internal waters," EU officials have said this could include warships or their helicopters to target pirate boats moored along the shoreline, or vehicles used by the pirates.

"The extension of the mandate until the end of 2014 confirms the EU's commitment to fighting piracy off the Horn of Africa," said Rear Admiral Duncan Potts, who commands the EU operation.

"Piracy has caused so much misery to the Somali people and to the crews of ships transiting the area and it is right that we continue to move forward in our efforts."