Five held after double murder:

Police investigating the double murder of two French volunteers on an island off Madagascar have arrested five suspects.

Authorities arrested four people who were at the same nightclub as the two victims on Sunday, but have not yet established a firm link to the murders.

Prosecutor Thierry Rajaona Lauret, who is running the investigation, said a fifth suspect — a French national living on the resort island of Sainte Marie — was arrested on Tuesday morning.

There is “no doubt” the two volunteers were murdered, police said. “We just need to determine a motive”.

The bodies of the two French citizens, a man and a woman aged in their 20s, were found Sunday on a beach of Sainte Marie with head injuries.

They had been volunteering at Cetamada, a local environmental non-profit organisation working to protect ocean mammals. (AFP)