News Corp's Fox television division has subpoenaed YouTube regarding programs posted on the video-sharing site, YouTube confirmed on Friday.

Fox advised YouTube that the programs were on the site without its permission and YouTube removed them in accordance with its policy, it said. YouTube has since received a subpoena and said it will comply with US legal processes.

The subpoena asks YouTube to provide information that could help Fox to identify the person who posted the videos, which include recent episodes of 24 and The Simpsons, according to a report in Friday's Wall Street Journal.

YouTube has faced several challenges regarding the unauthorised display of copyright content on its site, particularly since it was bought by search giant Google last year.

Japanese content producers have been trying to work with YouTube to prevent copyright materials from reaching its site, for example. Google has also received at least one legal challenge for displaying copyright videos: a French film company is suing it for including one of its films on Google Video.

Separately, Google announced on Thursday that it will integrate YouTube more tightly with Google video, although the sites will remain separate. For example, YouTube video results will appear in the Google Video search index. When users click on YouTube thumbnails they'll be taken to to see the videos. The company also alluded to plans for international versions of YouTube.