Ben Affleck has recently signed up to Twitter and is happy to have direct contact with his fans.

The movie star signed up to the social media site in June to highlight the child mortality rate in the Congo.

"I see how that kind of communication can be good and valuable and I really like the idea of people speaking directly to the audience," Affleck said.

The 39-year-old star turns 40 in August and revealed that he has been teasing close friend Matt Damon about his age: "Matt turned 40 before me and for two years we've been living in different decades.

"So I have been telling him about life from the youth perspective. You know, what it's like for guys in their 30s to a guy in his 40s. I'm not going to be able to make that taunt anymore, so that'll be disappointing."