Former England captain Alec Stewart said Kevin Pietersen had been right to complain of England players' Stuart Broad, Graeme Swann and Tim Bresnan's access to a parody Twitter account mocking the star batsman.
Pietersen, in a heavily-trailed autobiography which is on general sale on Thursday, has written of a "bullying" culture during his time within the England dressing room.
In particular, he did not take kindly to the 'KPgenius' Twitter account owned by Richard Bailey, a friend of England paceman Stuart Broad.
Pietersen's book states Bailey told Stewart he had insider help with the account.
However, Bailey has persistently denied this and on Wednesday he again insisted no England players had been involved, telling the Guardian newspaper: "They 100 percent did not tweet it."
But Stewart, South Africa-born Pietersen's coach at county side Surrey, contradicted Bailey's denial.
"The reason I am prepared to talk about is that he (Bailey) has said he didn't say anything to me and therefore is doubting my integrity and I won't have that," Stewart explained in an interview with BBC Radio Five on Wednesday.
"I'm not here to nail Pietersen, Broad, Swann, Bresnan. I'm an ex-England player and an England fan.
"What happened, back in 2012 at The Oval, this gentleman (Bailey) came up and said to me: 'I understand you follow the KPgenius twitter account'.
"I said 'yes, some of it is funny, some of it is close to the bone'.
He then said 'that is me', I said 'very good, well done'. He then came back and said, 'can I keep a secret?', I said 'yes, but it depends what you're going to tell me'.
"He said 'I can't tell you' and then walked away. Thirty seconds later he came back and said 'three players have access to the account, they have the password' and he told me the three names.
"The names were Bresnan, Broad and Swann and it didn't sit comfortably with me," added Stewart, England's most-capped player.
"Not because I wanted them three players to get fined, but it didn't sit comfortably with me if what he was saying was factually correct.
"I then made Hugh Morris (the then managing director of the England and Wales Cricket Board), and Andy Flower (then England coach, who is heavily criticised in Pietersen's book) at a later date, aware of the conversation, passed on that information and left it at that.
"If the ECB wanted to investigate or ignore, they could.
"I'm not going to doubt what Pietersen, Broad, Swann, or whoever has said but I will guarantee 100 percent this lad said that to me."
Ponting support
Pietersen's autobiography accuses England's senior bowlers and wicketkeeper Matt Prior of aggressively demanding apologies from team-mates not in their clique for any mistakes they made while fielding.
It was a claim supported by former Australia captain Ricky Ponting, who told the Sydney Daily Telegraph on Wednesday: "We saw them doing it, (James) Anderson was always the same, and Swann."
Pietersen, effectively sacked by England after their 5-0 Ashes debacle in Australia was completed earlier this year, responded to Ponting's comments by saying Wednesday: "I haven't even spoken to Punter (Ponting).
"When I woke up this morning and I saw this, one of the greatest cricketers to have ever played the game, how do you think he views it when he's in the opposition and he's seeing team mates abuse each other and bully each other on a cricket field?"
Pietersen's prospects of playing for England again appear slim but the 34-year-old – England's all-time leading run-scorer – insisted he had not given up hope of an international recall.
"Six months' time, you never know, there could be a change at the top, I live in hope," Pietersen said. "And one day I hope to be able to play Test cricket again."
The ECB have yet to respond to Pietersen's autobiography or Stewart's comments.
