There have been repeated calls for Mitchell to resign over claims he called police officers "plebs" in a foul-mouthed rant after being denied access through the Downing Street gates on his bicycle.
The Defence Secretary said yesterday that the Police Federation was using the issue as an excuse to bring up its own grievances with the Government.
Hammond said that Mitchell had apologised and would be returning to his duties as Chief Whip tomorrow.
He added: "I don't really buy the argument that he can't do the job. I think he can do the job."