Election 2015: Boris Johnson and Ed Miliband TV clash
Ed Miliband has clashed with Boris Johnson after the London Mayor called the Labour leader a "back-stabber".
In an article in the Sun on Sunday, Mr Johnson said he would never knife his own politician brother, Jo.
Mr Miliband claimed Conservative election strategist Lynton Crosby was behind the attack and urged Mr Johnson to sack him if he became Tory leader.
An unrepentant Mr Johnson said Mr Miliband "would do more damage to this country than he did to his brother".
The two men clashed on BBC One's Andrew Marr Show ahead of the 7 May general election. They had both been interviewed separately but were brought together on the sofa for a brief but noisy debate at the end of the programme.
Andrew Marr asked Mr Johnson if his attack on the Labour leader was fair.
'Get rid of Lynton'
Mr Miliband immediately cut in, saying: "Well, Lynton Crosby's putting him up to it.
"Come on Boris, you're better than this. Come on. Don't just do what Lynton says to you.
"If you become leader of the Tory party I'd get rid of Lynton if I were you. He doesn't do much for you."
Mr Johnson replied: "I'm not saying your brother had to present himself at A&E with a dagger in his back."
He pointed at the Labour leader and added: "He would do more damage to this country than he did to his brother and that is the key point."
Earlier in the campaign Defence Secretary Michael Fallon said Mr Miliband had "stabbed his own brother in the back" to lead Labour and was now "willing to stab the UK in the back" by doing a deal on Trident with the SNP "to become PM".
The Labour leader claimed the attack on him had dragged politics "into the gutter".
In 2010, Ed Miliband defeated his older brother David in a contest to become Labour leader.
The Sun of Sunday had styled Mr Johnson as "the Bozfather" in a piece emphasising family loyalty.
Boris Johnson, who pointed out during the Andrew Marr Show that he and Mr Miliband had attended the same primary school, is hoping to get back into Parliament at the election - his brother Jo is also hoping to get re-elected as an MP.
Mr Johnson, who is serving his second term as the elected Conservative Mayor of London, is widely tipped as a possible successor to David Cameron as party leader.
Andrew Marr watched as the two politicians faced each other and joked, perhaps referring to possible future Prime Minister's Questions clashes: "I have a premonition that this is things to come."