The government's Covid catch-up National Tutoring Programme will reach 750,000 pupils when it is "fully rolled out", the schools minister said today.
However, this figure represents barely half of the 1.4 million children on free school meals that Labour believes should benefit from the scheme as a minimum.
Last week education secretary Gavin Williamson said he expected to see a "considerable expansion" to the 120,000 pupils helped by the NTP to date, following the latest boost to the Covid catch-up fund.
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However, he "struggled to pinpoint" the total number of children that would benefit.
Taking questions in the House of Commons today, schools minister Nick Gibb said the scheme would help "three-quarters of a million" disadvantaged pupils to recover lost learning.
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"Both the National Tutoring Programme and the academic mentors will reach three-quarters of a million disadvantaged pupils once it's fully rolled out," Mr Gibb said.
"We are absolutely determined, as a government, to ensure that all children are able to catch up, particularly the most disadvantaged pupils in our country."
Questioning Mr Gibb on the issue, shadow schools minister Wes Streeting indicated Labour thought the scheme should help at least all pupils on free school meals.
"Last week, the secretary of state confirmed that 120,000 pupils have been reached by the National Tutoring Programme, reaching fewer than 10 per cent of all children on free school meals," he said.
"Given that we know that the need for additional tutoring support will extend to all pupils on free school meals, and many more besides, how can the government have the brass neck to claim they are doing all they can to tackle disadvantage, and being ambitious for children [and] our country's future, when their flagship scheme is reaching only a fraction of those pupils that need additional support?"
The news comes on the day that Tes revealed new findings suggesting that more than four in five heads in the North East are not using the NTP.
Of the 135 school leaders who responded to a survey by the Schools North East network, 19 per cent said they had participated in the scheme, while 81 per cent said they had not.