In the statement released through their lawyers, the pair said they were "saddened to announce their separation", People magazine reported.

"Kate and Sam are saddened to announce that they separated earlier this year," the statement read. "The split is entirely amicable and is by mutual agreement. Both parties are fully committed to the future joint-parenting of their children. They ask that the media respect the privacy of the family."

The pair, who married in 2003, have one son together aged six and Kate has a daughter from her previous marriage to director Jim Threapleton.

Sam directed 34-year-old Kate in Revolutionary Road, a story about a marital breakdown, for which she won a Golden Globe for best actress.