The government is investigating an allegation of financial irregularity at an academy trust previously praised by Prime Minister David Cameron.
Department for Education officials are looking into the concerns raised about Perry Beeches Academy Trust, which runs five schools in Birmingham.
It is headed by Liam Nolan who received plaudits from former education secretary Michael Gove.
Both Mr Gove and Mr Cameron attended the opening of the Perry Beeches III free school in 2013, describing it as the future of British education.
But it was placed into special measures by Ofsted earlier this year, sparking four resignations.
A DfE spokesman said today: “We have received allegations about possible financial irregularity at Perry Beeches Academy Trust.
“It would not be appropriate to comment further at this stage.”
Perry Beeches Academy Trust has been contacted for comment.