Friends star Aniston in TV sitcom

It is not known when Aniston's episode will be aired

Actress Jennifer Aniston is filming a guest appearance on US comedy 30 Rock.

The 39-year-old rose to fame playing Rachel Green in Friends, which was also shown on the NBC TV network.

30 Rock, starring Tiny Fey and Alec Baldwin, is a behind-the-scenes spoof of a TV network and the huge corporation that owns it.

The third series of the Emmy Award-winning sitcom starts in October. It has featured a number of guest appearances by big names from showbiz.

Aniston's Friends' co-star David Schwimmer appeared in an episode of 30 Rock during the last series.

Since the hugely-successful Friends ended in 2004, Aniston has concentrated on films, including Friends with Money and The Break-Up.

In July, Warner Brothers film studio told the BBC there were no plans for a rumoured big-screen version of Friends.

Since the success of the Sex and the City movie, there has been constant speculation that the US sitcom's six stars had agreed to their own film.