Photo: The Canadian Press. All rights reserved.

An online streaming website shows a description of American TV show "The Big Bang Theory" but it no longer have access to episodes in the series on a computer screen in Beijing Sunday, April 27, 2014.  (AP Photo/Ng Han Guan)

Chinese authorities have ordered video streaming websites in the country to stop showing four popular American TV shows, including "The Big Bang Theory" and "The Good Wife," representatives from two sites said Sunday.

The move suggests government attention is intensifying on the online streaming industry, which is freer than state television and China's cinemas to show foreign productions and other content.

A spokeswoman for a leading online video site, Youku, said it had received notification on Saturday not to show sitcom "The Big Bang Theory," political and legal drama "The Good Wife," crime drama "NCIS" and legal drama "The Practice." Of those, Youku showed only "The Good Wife." The State Administration of Press, Publication, Radio, Film and Television didn't give a reason for its order, said the spokeswoman, who couldn't be named because of company policy.

A senior manager at another site, who spoke on condition of anonymity because of the sensitivity of the issue, said it received the surprise order last week to "clean their website." The order, which was identical to the one sent to Youku and other companies, also listed a Chinese slapstick miniseries made by another site, Sohu, as having to be removed, said the manager.

Calls to the State Administration of Press, Publication, Radio, Film and Television rang unanswered Sunday, and Sohu did not immediately respond to a request for comment.

Online streaming sites regularly receive orders to take down Chinese or foreign TV programs and movies, but usually because the regulator considers them to be too salacious or violent or because they infringe copyright laws. Sohu's most popular U.S. shows are "Nikita" — episodes from the first and second seasons have been watched a combined total of 472 million times — and "Masters of Sex," which weren't included in the order.