Chinese online video sites say authorities have ordered them to stop showing four popular American TV shows, including 'The Big Bang Theory' and `The Good Wife.'

The move suggests government attention is intensifying on the online streaming industry, which is less regulated than state-controlled television.

A spokeswoman for Youku said the State Administration of Press, Publication, Radio, Film and Television didn't give a reason for its order.

A senior manager at another video streaming site said it received an order last week to `clean their website.'