Billy Crystal and John Goodman voiced the lead roles in the original Monsters Inc

Pixar's 2001 film Monsters Inc - about monsters who scare kids for a living - is to have a sequel, the Disney studio has announced.

The animated follow-up will be released on 16 November 2012, Disney chairman Rich Ross revealed.

Another Pixar film, The Bear and the Bow, is to be renamed Brave and have its release put back from December 2011 to 15 June 2012.

Disney is also to make a new Muppets movie, Ross confirmed on Thursday.

The film, to be directed by Flight of the Conchords creator James Bobin, will introduce a new puppet character called Walter.

Featuring the voices of Billy Crystal and John Goodman, Monsters Inc made more than $525m (£342m) worldwide.

It is not known if its director Pete Doctor - who went on to make the Oscar-winning Up - will direct its sequel.

Featuring the voices of Reese Witherspoon and Billy Connolly, Brave tells of a Scottish princess who dreams of being an archer.

Set in 18th Century Scotland, Brenda Chapman's movie is the first Pixar feature to be directed by a woman.

Other future projects from Disney-Pixar include a retelling of the Winnie the Pooh story using hand-drawn animation and Frankenweenie, a stop-motion cartoon based on a story by Tim Burton.

Pixar release Toy Story 3 this summer, with a Cars sequel due in cinemas next year.