Ofsted chief inspector Sir Michael Wilshaw has claimed today that multi-academy trusts have “manifested the same weaknesses” as the worst-performing local authorities and “offered the same excuses”.

In an explosive letter to education secretary Nicky Morgan today, Sir Michael said he has “great concern” about the performance of seven large multi-academy trusts (MAT) that were inspected by Ofsted.

He said the findings of the focused inspections were “worrying” and highlighted “serious weaknesses”. Trusts named in the letter included E-ACT, School Partnership Trust Academies (SPTA) and Academies Enterprise Trust – the country’s largest MAT with 67 schools.

He claimed one chief executive – who he did not name – blamed parents for pupils’ poor attendance that was affecting their performance.

His comments will come as a blow to the government as it continues its drive towards a fully-academised system.

Sir Michael said: “There has been much criticism in the past of local authorities failing to take swift action with struggling schools.

“Given the impetus of the academies programme to bring about rapid improvement, it is of great concern that we are not seeing this in these seven MATs and that, in some cases, we have even seen decline.”

He said many of the inspected trusts were failing their poorest children – despite the academies movement initially being established to improve the performance of disadvantaged pupils.

AET and SPTA were highlighted, citing a gap of 25 percentage point gap between disadvantaged pupils and their peers at level 4 and above. The national average is 17 percentage points.

He then attacked the pay of trust chief executives, saying “some do not appear to be commensurate with the level of performance of their trusts or constituent academies”.

He said the average pay of the seven trusts’ chiefs was higher than that of the prime minister’s £140,000.

Trusts are also holding “very large cash reserves”, Sir Michael said, totalling £111 million as of August last year. He added some are spending money on expensive consultants – at least £8.5 million in 2014/15 alone.

Sir Michael took a final swipe over the geographic spread of schools in some academies, adding: “It is clear that, with such a vast spread of diverse provision, these particular trusts are still struggling to monitor performance effectively.”

He added: “If we are to improve national standards in an increasingly autonomous system, much more needs to be done to reduce the variation in standards between the best and worst academy trusts.”

The Department for Education said the report focused on seven chains that had been identified as “causing the most concern”. A spokesperson said: “It is a partial and skewed picture and no reflection on the success of the MAT model as a whole.

“No child should spend a single day in a failing school and work is already underway in all of these cases with Regional School Commissioners challenging these chains to show how they will improve and where that is not happening taking swift action – a sharp contrast to days when underperforming schools were left to languish under local authority schools. However there are many great MATs driving up standards and delivering an excellent education to children across the country, thanks to their ability to share resources, expertise and provide support to schools that may be struggling.”