Matt Damon was ''covered'' in poo while filming 'Elysium'.

The actor had the unenviable task of filming scenes in one of the world's largest rubbish dumps, Poo River in Mexico, for his new sci-fi blockbuster and reveals he faced serious health risks.

He said: ''We had one location in the dump that was called Poo River. Literally, it was like, 'OK, can we get everybody down to Poo River for Scene 36?' ''

Damon explains that matters were made worse when a helicopter flew overheard attempting to catch aerial shots of the scene and inadvertently covered him in faeces.

He explained: ''He kept coming in too low and was blowing Poo River all over us. We literally ate s**t. we were covered in it. If anyone has ever been in the rotor wash of a helicopter, it can be really severe.

''It was tough ... we were all told we had to get rid of the clothes that we wore each day. There was enough faecal matter to get sick and that was the big fear - that we might get respiratory illness from just breathing it in.''

Despite the on-set troubles, the Oscar-winning actor admits he jumped at the opportunity to work with 'District 9' director Neill Blomkamp because he's a huge fan of the film.

He told the Metro newspaper: ''I freaked out like everyone when I saw 'District 9'. Neill was instantly top of the list of people I wanted to work with. I didn't think I would get to work with him right away but, sure enough, on his next movie there was this role available.''