The government’s former education catch-up tsar, Sir Kevan Collins, has said the approach to the issue had been “a bit feeble” and that a “massive national effort” is now required.

Giving evidence to the Commons Education Committee, he said: “Our country has responded in a way which, compared to some others, is frankly a bit feeble. This scale of shock…requires a massive national effort to recover.

Exclusive: Sir Kevan Collins resigns over catch-up plan

Related: Sir Kevan Collins’ decision to quit ‘is a real blow’

Background: No extended school day in new £1.4bn catch-up plan

“I worry that it is not a bit of tutoring in the corner, it is actually a fundamental approach the school needs to take.

“That is why I was keen to see a whole-school effort, around time, around teaching, around tutoring, and not a narrow kind of auxiliary attention to one particular activity that can get put to a teaching assistant.”

Sir Kevan said that education inequality could be the “legacy of Covid” and suggested that longer school days could be a way of tackling this.

The former catch-up tsar told MPs: “I’m personally very, very clear that the biggest impact of Covid will definitely be on our most disadvantaged children.

“The growing education inequality could be the legacy of Covid if we’re not very careful. We have to intentionally and directly intervene, support the children with the greatest need.

“Every child we have obligations to, after Covid, and that’s why I think the longer time would have supported every child, particularly with the non-academic outcomes - wellbeing and social stuff.

“But when it comes to the academic loss, I think it’s clear that we’re going to see greater loss for our children who have greatest need.”

“I was very disappointed, obviously, that I had to resign,” Sir Kevan told MPs, but the package offered “just wasn’t enough to deliver the kind of recovery we need”.

He said: “The proposal that came forward, as I said in my article and in my letter to the prime minister, just wasn’t enough to deliver the kind of recovery we need.

“I was given a very ambitious but very exciting exam question by the prime minister, which was to recover every child in this Parliament.

“And I set about examining the evidence and the approaches that will allow us to deliver that ambition.”

Sir Kevan said it had been a “very, very difficult decision” to resign but that he felt he had been left with no choice.

He said the amount of money the government was prepared to commit had fallen too far short of what he believed was necessary.

“It was a very, very difficult decision. It wasn’t what I wanted to do,” he said.

“I did consider all the options, but the quantum was so different from the amount that I thought we needed to deliver the exam question I was asked, that it was impossible for me not to step back at that point.”

Sir Kevan said he was “very worried” about “complacency” and the belief that children’s education would recover naturally.

“Of course, we have to do more. We cannot blight a generation of children by not investing in their education,” he said.