Robert De Niro, Diane Keaton in wedding film

Robert De Niro has signed up to a new comedy penned by The Bucket List writer Justin Zackham.

The actor will co-star with Diane Keaton in Gently Down the Stream as one half of a long-divorced couple forced to pretend they are still together for their adopted son on his wedding day, Variety reports.

Zackham said: "I'm excited to be able to continue what we started with on Bucket List – iconic actors in a funny, adult, character-driven story, albeit with a little more sex and bad behaviour on everyone's part."

De Niro recently committed to his ninth collaboration with Martin Scorsese, an adaptation of the Charles Brandt novel I Heard You Paint Houses.

Zackham has also produced a script about the Britain's Got Talent winner Paul Potts's rise to fame, which is to be directed by David Frankel.