An investigation is being carried out into "non-recent safeguarding concerns" relating to Soul Survivor founder Mike Pilavachi.
The "difficult news" of the investigation was shared in two statements read out during the services at Soul Survivor Watford on Sunday.
Pilavachi has agreed to step back from all ministry while the investigation is carried out.
The statements stressed that it was not a criminal investigation.
"We would like to stress that the police are not involved; this is not a criminal investigation and Mike has not been suspended. It is also not currently a clergy disciplinary matter," the first of the statements said.
It continued, "We really appreciate your prayers for all those involved at this very difficult time and we do ask, for the sake of all those involved, that you do not speculate or discuss this more widely, including on social media while the process runs its course. This is to be fair to everyone involved."
Soul Survivor said it was working closely with the Diocese of St Albans and that the investigation was being carried out by the Church of England according to the House of Bishops guidelines.
No date was given for the conclusion of the investigation.
Rev Andy Croft, Senior Pastor of Soul Survivor Watford, has stepped back from his role as chair of the church's trustees while the investigation is carried out "due to his close personal relationship with Mike".
Acting chair David Mitchell told the congregation that the concerns "currently relate to matters which occurred a considerable time ago".
"Nothing should be inferred from Mike stepping back; this is perfectly normal following the start of an investigation that has not reached a conclusion," he said.
"We mutually agreed this was the best step because of the importance of correct procedures being followed."
He ended, "We understand this may be very difficult information to absorb," before adding, "We are going to keep our focus on Jesus and what he is calling us to do."
Anyone with safeguarding concerns relating to these statements can contact Jeremy Hirst at the Diocesan Safeguarding Team at safeguarding@stalbans.anglican.org or Ian Bowles or Anthony Clarke at the National Safeguarding Team at safeguarding@churchofengland.org.
