Paul Bettany has admitted to some regrets about passing up the lead role in The King's Speech.

Family commitments meant the English actor had to turn down the part of King George VI, for which Colin Firth has since received a Golden Globe and an Oscar nomination.

"Number one, of course, it is a regret not to be working with such great, and really great people, Geoffrey Rush and (director) Tom Hooper," Paul said.

"I think it is a little inelegant for me to discuss it... I had been working for five months steadily and my son missed me and I missed my son. Both of my sons and my wife," he added, referring to his work on The Tourist as Inspector John Acheson.

Screenwriter David Seidler has revealed he wrote The King's Speech - up for 12 Oscars - with Paul in mind to play the stammering monarch, and Geoffrey as his speech therapist.

Speaking at the Sundance Film Festival Paul, who is married to actress Jennifer Connelly, insisted his wife and two kids always came first.

He said: "I regret not working with such amazing, amazing actors and directors and writers. But no, I have to do the right thing by my family every time."