A university-backed academy chain has been warned it must raise its game amid concerns about standards at three of its schools.
Schools minister Lord Nash has issued a "pre-warning notice" letter to the directors of the University of Chester Academies Trust, (UCAT) saying that there has been a "serious breakdown" in the way some of its schools are managed and governed.
The letter highlights three of the Trust's academies - the University of Chester Church of England Academy (UCEA), The University of Chester Academy Northwich (UCAN) and the University Academy Liverpool (UAL), where performance standards are "unacceptably low".
It says that that at UCEA, which opened in 2009, results are "variable", with 45% of pupils gaining at least five C grades at GCSE, including English and maths, last year.
Although this is above the Government's floor standard, not enough progress is being made in the basics, Lord Nash wrote, adding that Ofsted placed the school in a category of concern last October.
At UCAN, which has been placed into special measures, just 39% of teenagers got five or more A*-C grades in their GCSEs last summer including English and maths, which is below the Government's benchmark, the letter says.
And at UAL, which like UCAN opened in 2012, GCSE results were also below the national floor standard, with 33% getting five good grades including the basics. Its performance could mean that it is put into a category of concern by Ofsted, Lord Nash said.
At both of these academies pupils are also not making enough progress in English and maths, he added.
The minister wrote: "The Secretary of State and I are therefore satisfied that the standards of performance at these three academies are unacceptably low."
The Trust is currently responsible for sponsoring nine academies across the north-west of England.
Lord Nash also warned the organisation to reconsider its co-sponsorship of two more academies - The Winsford E-ACT Academy and Ormiston Bolingbroke Academy.
"I understand you are already in discussions with officials to step back from sponsorship at Winsford and plan to do this shortly," he wrote.
"I would urge you to do the same with Bolingbroke Academy, so that you are able to focus on the schools where you are lead sponsor."
UCAT was among a list of 14 academy sponsors, published in March, which have been barred by the Department for Education from taking on more schools.
The list of chains stopped from taking on new projects was published following a parliamentary question.
The new letter also comes just months after an academy backed by another university - Nottingham, - was ordered by ministers to improve amid concerns about standards. The governors of Nottingham University Samworth Academy (NUSA) received a "pre-warning" letter saying the school must boost its performance.
The university said at the time that it was putting a plan of action in place to improve teaching and learning and to strengthen management and leadership.