George Clooney is "nervous" about becoming a father.

Amal and George Clooney

Amal and George Clooney

The 'Monument's Men' star is expecting twins with his wife Amal Clooney and whilst he is looking forward to expanding his family, he is reportedly a little anxious about the whole thing.

A source said: "George is excited but nervous. He is excited about the kids, but also has the normal amount of nerves that come with being parents ...

"Amal strikes me as someone who'll be a fantastic mother. Intelligent, loving, funny, smart, nurturing. She doesn't seem someone who will let kids get away with being Hollywood children."

And it has been claimed that the couple have been planning for a family for a little while after George is said to have told a pal he "might be taking some time off" in the future.

An insider added to People magazine: "Amal stopped traveling for dangerous missions months ago.

"George knows how brilliant Amal is in her work and how nurturing of a person she is. He knows she will be a wonderful mother ...

"[George had previously] hinted that he might be taking some time off. That would be very rare for him, but now it all adds up. He's going to be the best dad."

And it's not a surprise that George might be feeling nervous as his pal Matt Damon recently joked he doesn't know how "anyone" could bring up twins.

He said: "[George] said to me, 'Well, you have four.' And I said, 'Yeah, but not at once!' We did it one at a time. I don't know how anybody does twins. Those sleepless nights ... and there's two of them? There's just no way. But we'll see."

Matt was one of the first people to know about the impending arrival as he recently revealed George told him before the 12 weeks mark.

He shared: "I was working with him last fall and he pulled me aside on set and I mean, I almost started crying. I was so happy for him. And I was like, 'How far along is she?' And he goes, 'Eight weeks.'

"[I said,] 'Are you out of your mind?! Don't tell anybody else! Don't tell anybody else! Don't you know the 12-week rule?' Like of course he doesn't. 'Just shut up, man.' And then four weeks later, I'm like, 'We're good right?' [George confirmed] 'We're good.'"