Australia have a 268-run lead over England going into the fourth day of the second Ashes Test

Australia have verbally abused England players over an issue which "hasn't come out for various reasons", former wicketkeeper Matt Prior has claimed.

The three-time Ashes winner, who played in 79 Tests for England before retiring in 2015, added some insults had "rightfully" upset some players.

Australia players have admitted targeting the tourists with "smarter" sledging during the Ashes series.

However, they have denied their comments have overstepped the mark. external-link

When asked if, "hand on heart", he was comfortable with what his players had said on the pitch during the first Test in Brisbane, Australia captain Steve Smith said: "I think the umpires and match referees are there to determine that."

After being bowled out for 227, England reduced Australia to 53-4 in their second innings to trail by 268 runs going into the fourth day of the second Test in Adelaide. Australia lead the five-match series 1-0.

Prior told BBC Radio 5 live: "There's a lot that's gone on that I think the England players are quite upset about - and rightfully from what I've heard.

"There's been a lot of chat on the pitch that hasn't got anything to do with cricket and frankly shouldn't be on a cricket pitch - stuff that hasn't come out, for various reasons."

Prior refused to go into further details about what the issue was but said ordinarily sledging would not affect senior players such as former England captain Alastair Cook or Australia batsman David Warner.

He added: "Simple sledging doesn't really work on these top international players. Alastair Cook is not going to be affected by sledging, Steve Smith, Warner - these guys have seen it, they've done it. So therefore you have to go deeper if you want to try and get a reaction and say something that's going to be pretty fiery and potentially personal."

England wicketkeeper Jonny Bairstow's 'headbutting' of Australia's Cameron Bancroft in a Perth bar at the start of the tour only emerged when comments were picked up on a stump microphone.

Smith later said his side used sledging to unsettle Bairstow, while batsman Peter Handscomb said Australia's sledging in Brisbane was some of the "smartest" they have employed.

England coach Trevor Bayliss has attempted to play down the issue of sledging during the Ashes, though he has called for stump microphones to be turned down so that "young kids watching at home" do not hear what is being said.