Tunisian Oussama Mellouli added the 5km world title to his 10km Olympic crown in the open water event at the World Swimming Championships in Barcelona on Saturday.

American Haley Danita Anderson won a photo-finish to claim gold in the women's 5km event to improve on the silver medal she gained at the Olympics in London last year.

It was a second world title for Mellouli who also triumphed at the 1500m in the pool in Rome in 2009.

He beat Canadian Eric Hedlin into silver with Germany's Thomas Lurz winning bronze.

Anderson pipped Brazilian Poliana Okimoto by just two tenths of a second with Ana Marcela Cunha, the current 25km world champion, also from Brazil, third.