An investigation is under way after a US foreign service officer was found dead in Madagascar, the US state department says.

The unnamed officer was found at their residence overnight on Friday, a statement said.

A suspect is in custody and both US and Madagascan officials are investigating, it added.

A man was caught trying to jump over the fence while fleeing the house, a Malagasy police spokesman told AFP.

The island nation, off the south-east coast of Africa, has experienced repeated political instability and is one of the poorest countries in the world.