Britain's Royal Navy has captured 13 suspected Somali pirates after ships from a NATO-led counter-piracy force intercepted their boat in the Indian Ocean, the Navy said.

A Royal Navy auxiliary ship, RFA Fort Victoria, and a U.S. Navy destroyer, the USS Carney, were sent to investigate a suspected pirate dhow off the Somali coast on Friday, the Navy said in a statement.

British Royal Marines using speedboats boarded the dhow after it ignored warnings to stop, and found 13 suspected Somali pirates and a selection of weapons on board, the statement said.

A spokeswoman for the Royal Navy in Bahrain, Lieutenant-Commander Heather Lane, said on Saturday that the suspected pirates were still on board their vessel, which she said was in a poor condition.

We are investigating the evidence on board. They will be transferred some time later in the day to RFA Fort Victoria, she said. She did not say where they would ultimately be taken.

Pirates operating from the Somali coast have raked in hundreds of millions of dollars in ransoms from hijacking ships, and continue to pose a threat to shipping despite international efforts to stop them.

Britain will host an international conference on February 23 to try to agree on measures to tackle instability and piracy in the east African country.

(Reporting by Adrian Croft; Editing by Alessandra Rizzo)