News Corporation's Rupert and James Murdoch have been summonsed to appear before MPs to answer questions on the phone-hacking scandal on Tuesday. But as US citizens, Rupert Murdoch, who has declined a request to attend the Commons media committee, and his son James, who has offered to go on another day, cannot be forced to appear. News International chief executive Rebekah Brooks has agreed to attend.Rupert Murdoch has said he will appear before the judge-led public inquiry.Meanwhile, a 60-year-old man arrested on Thursday is understood to be Neil Wallis, the former executive editor of the News of the World.