Sadiq Khan: Corbyn 'very unwise' at Battle of Britain ceremony
Khan also attacked Shadow Chancellor John McDonnell over comments about "honouring" IRA terrorists.
Speaking to the Mail on Sunday about Mr Corbyn's behaviour, Mr Khan said: "He was very unwise. You are trying to be the British Prime Minister: you should be singing the National Anthem. It was a mistake, especially on that occasion. You have to show respect. You may have strong views about the National Anthem. But you want to be the British PM? It was the Battle of Britain commemoration."
He also unequivocally condemned Mr McDonnell's remarks in 2003, for which he apologised on Thursday.
"Language is very important. If you are condoning acts of terror… you are giving credibility to a view that is perverse and is wrong," Mr Khan said.