London - Video footage of self-proclaimed racist Chelsea fans pushing a black man off a Paris metro train was "extremely disturbing and very worrying", British prime minister David Cameron said on Wednesday.
"It's obviously potentially a criminal offence and so I'm sure the French police will be looking at it very seriously," Cameron told London radio station LBC in an interview.
"I know the British police will give every assistance that they can. I'm sure Chelsea will co-operate with that fully. These are very very serious matters."