Nicky Butt has been appointed the new head of the Manchester United academy

Nicky Butt had an astonishing training ground bust-up with new Man United director of football John Murtough before he quit the club, Football Insider can exclusively reveal.

The duo went head to head at the Aon Training Complex following a verbal exchange that was said by witnesses to be explosive.

A Man United source has told Football Insider that Butt, 46, and Murtough were “nose to nose” and “nearly came to blows” as they exchanged “four-letter insults”.

Celtic

The bust-up, which happened around six months ago, summed up the fractious relationship between the pair.

As one source put it, “John was lucky it did not come to blows as Butty would have killed him, he was ready to really go for him”.

The Premier League giants announced on Wednesday that United legend Butt had quit the club’s academy after nine years for a “new professional challenge”.

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He could be headed to Celtic as part of a new-look management team headed by his longstanding former teammate Roy Keane, who is the frontrunner to be Neil Lennon’s successor.

As revealed by Football Insider, Keane has opened discussions with Celtic and was interviewed by the board earlier this week.

The United coaches are said to be fuming at the departure of Butt.

The source explained that the straight-talking former England midfielder “is Man United through and through”, and had no time for Murtough, widely regarded as the “eyes and ears of Ed Woodward”.

He was promoted to become United’s first-ever director of football earlier this month after previously being their head of football development.

That appointment was the final straw for Butt, who felt he could not work with someone he did not trust.

In other news, Bruno Fernandes to help Man United lure ‘phenomenal’ £40m talent this summer.