Two aid workers, an American woman and a Danish man, being held by pirates in Somalia, have been freed after a rescue mission by US special forces.

Military helicopters ferried elite troops to the pirate camp where a shootout secured the release of the pair, held hostage since October last year. Neither Jessica Buchanan, 32, nor Poul Hagen Thisted, 60, were injured in the assault but nine of their captors were said to have been killed.