David Warner has been stood down from Australia's Champions Trophy match against New Zealand after what has been called "an unprovoked physical attack" on Joe Root in a Birmingham bar in the early hours of Sunday morning.

Warner could yet face further sanction, including the possibility of being sent home from the tour, depending on the outcome of a Code of Behaviour hearing, which Cricket Australia said would be convened as soon as possible.

The ECB confirmed in a statement that an altercation between Warner and an England player took place and said it was initiated by Warner. They said the player was not responsible for the incident which happened around 2am following England's 48-run victory at Edgbaston, and had accepted an apology from Warner.

"Following a statement issued this morning by Cricket Australia, the England and Wales Cricket Board confirms that David Warner initiated an unprovoked physical attack on a member of the England team in a Birmingham bar following England's 48-run victory over Australia," the ECB said in a statement. "Warner has admitted behaving inappropriately and has since apologised to the player involved who has accepted the apology.

"Following a full investigation the England team management has concluded that the England player was in no way responsible for nor retaliated to the attack. ECB has concluded that this is a matter for Cricket Australia and have no further comment to make."

Alastair Cook, the England captain, said that his players were fully within their rights to be out in the early hours of the morning. "You don't often get to win international games," he said. "When the schedule allows you, as long as its within certain parameters that we set as a team [and] we didn't have training for a couple of days.

"Clearly if it was a back-to-back game it's a very different issue. We had a couple of days off and a couple of days training, you don't often get those positions in a tournament so it's very important you do sometimes let your hair down. Celebrating wins also builds team spirit."

John Creighton, manager of the Walkabout bar in Birmingham, said: "David Warner and Joe Root were in our VIP area between 1.30am and 2.30am on Sunday morning along with several other England and Australia team members. None of the group seemed to have been drinking to excess and just seemed to be having a good time. There was a small altercation between Warner and Root.

"This was dealt with very amicably and quickly by the rest of the group and both were calmly chatting to each other shortly afterwards. They all left a short while later and a small bar tab was picked up by David Warner. We are quite familiar with David's face."

The manager added he did not think Warner's punch connected although it is understood that some contact was made. He also confirmed that police were not called although it is believed that was at the behest of Root who did not want to take the matter further.

Warner was reported under Cricket Australia's Code of Behaviour and in a statement, Cricket Australia said he had been cited after he "was allegedly involved in a physical altercation with an England player in the early hours of Sunday morning following the ICC Champions Trophy match between the teams in Birmingham".

The incident could have serious ramifications for Warner's Ashes campaign. He has been cited under Rule 6 of the Code of Behaviour, which deals with unbecoming behaviour, and states that: "Players and officials must not at any time engage in behaviour unbecoming to a representative player or official that could (a) bring them or the game of game into disrepute or (b) be harmful to the interests of cricket."

It is the second time in four weeks that Warner has been reported under that section of CA's Code of Behaviour, after he was fined $5750 last month for engaging in a Twitter spat with two Australian journalists. Following that incident, Warner said: "I just want to draw a line under all of this and move forward."

Warner has also been struggling for runs since arriving in England, having made ducks in both the Champions Trophy warm-up games and 9 in the loss to England.

Brydon Coverdale is an assistant editor at ESPNcricinfo. He tweets here