Education secretary Gavin Williamson was accused of presiding over a “summer of chaos, incompetence and confusion” as he appeared in the House of Commons this afternoon.

Labour called on ministers to “learn from their mistakes” following the exams grading U-turn.

Mr Williamson said he was “deeply sorry” to students caught up in the affair.

Related: Decision ‘very soon’ on whether to delay 2021 exams

News: Ofqual proposes late GCSE start date for 2021

Exams: ’Unrealistic’ to run full GCSE course in most subjects

“The independent regulator, Ofqual, had put in place a system for arriving at grades that was believed to be fair and robust,” Mr Williamson said.

“It became clear, however, that there were far too many inconsistent and unfair outcomes for A- and AS-level students, and that it was not reasonable to expect these to be dealt even through a boosted and enhanced appeals process.”

GCSE and A-level results: ‘A great deal of stress and uncertainty’

Mr Williamson continued: “This situation has, I know, caused a great deal of stress and uncertainty, and I am deeply sorry that those who have borne the brunt of it have been students themselves.

“I can only apologise to them again for this.” 

Shadow education secretary Kate Green accused Mr Williamson of presiding over “chaos”.

“I’m welcoming the secretary of state back to his place after a summer of chaos, incompetence and confusion that has caused enormous stress to children, young people, their families and their teachers,” she said.

“Ministers must now learn from their mistakes and ensure that keeping schools open and pupils learning is a national priority.”

Mr Williamson said he was “confident” the necessary preparations were in place for schools to return.

He said welcoming pupils back would be a “massive milestone” for schools, and highlighted a letter from the four UK chief medical officers about the “low risk of long-term harm from Covid-19 due solely from attending school in comparison to the higher risk of long term from not attending school”.

Mr Williamson said pupils were returning to a “safe environment”, telling the Commons: “I know that these past few months have been some of the most challenging that schools, parents and, most of all, children have faced.”

Mr Williamson also challenged Labour over Ms Green’s criticism of the government regarding possible delays for GCSEs and A levels in 2021.

He told MPs: “On 2 July, Ofqual did a public consultation about potentially moving the exam dates back.

“I’ve been to check as to whether the Labour Party made a submission as to whether they supported this.

“The Labour Party did not make a submission supporting the idea of moving exams back, so I very much welcome the Labour Party to our position.”

He said that he was determined exams and assessment would go ahead next year.

But Geoff Barton, general secretary of the Association of School and College Leaders, said: “We are surprised that the secretary of state did not provide any more information about next year’s GCSE, A-level and other qualifications.

“He appeared to say at one point that the government supported delaying the exam series to a later date than normal, but we are not aware of any decision having been made to this effect.”

Mr Barton said there was still no “contingency plan” in place if pupils are unable to sit exams next year, adding that there needed to be a “review” of this year’s grading process to ensure that mistakes were not repeated.

“On the reopening of schools and colleges, this is clearly a big step forward in terms of national recovery, which is being led with great commitment and determination by school and college leaders and their staff,” he said.

“It is hugely disappointing that the government has refused to support them by providing funding to cover the significant cost of safety measures and has instead said it must come out of hard-pressed budgets.”