Kevin Pietersen holds the key to whether he ever again plays for England, team coach Andy Flower said yesterday.

The South Africa-born batsman has been omitted from England's defence of their ICC World Twenty20 crown in Sri Lanka next month, and the squad to face his native country in five one-day internationals (ODIs) and three Twenty20s this month and next.

Until Pietersen speaks face to face with his England and Wales Cricket Board employers and management, no progress can be made for his possible reintegration into the team in any format, Flower confirmed.

England are understood to be significantly concerned about the exact content of text messages Pietersen sent to opposition players during the drawn Test against South Africa at Headingley.

They reportedly included derogatory references to his Test captain Andrew Strauss – and when Pietersen did apologise for them, as the ECB requested, he acknowledged they were "provocative".

Flower yesterday made it clear the text messages are not the only issue in a "very sad situation".

"There are deeper issues, certainly of trust and mutual respect that need to be addressed. Issues have to be resolved before there is any way forward. You resolve these face to face with people, not through PR agencies. If this is going to get resolved, that is how it's going to have to be.

"He played superbly at the last Twenty20 World Cup, but the circumstances mean he can't be selected. There are unresolved issues, and we will be addressing those when we have time to do so."

Pietersen was dropped for the Lord's Test – lost on Monday by 51 runs, as England went down 2-0 in the Investec series to South Africa and also conceded their world No.1 status to those opponents.

Flower added: "Let me be clear – this is not just an issue between the captain and Kevin. Andrew Strauss and I have worked very closely and very well together over the years, and we will continue to do so over this issue."

Pietersen's contract wrangles with the ECB – specifically over his initial wish, since retracted, to next year play a full Indian Premier League season at a time when England have Test match obligations – have been ongoing all summer, and three months ago brought his retirement from all international limited-overs cricket.

That position has also been revised, but many observers fear that aged 32 Pietersen may effectively have called time on his England career.

Strauss has been equivocal about his future as England captain, but Flower yesterday gave him an unqualified endorsement.

"He's a superb leader," the coach said. "He can certainly take this side on. He deserves a little break and he's taking it now. He'll come back feeling refreshed, I'm sure."

Twenty20 captain Stuart Broad has been omitted from the ODIs – starting on Friday in Cardiff – to give him a rest before a packed schedule.