Poorer pupils could be up to eight months behind at school after the pandemic and catch-up plans are failing to reach them, MPs have warned.
Covid school closures had a "disastrous impact" on children's education, with disadvantaged kids worst hit by months out of the classroom, the Commons Education Committee said.
MPs said pupils are facing an "epidemic of educational inequality" and a "worsening mental health crisis" because of school closures and repeated lockdowns.
Tory Robert Halfon, chairman of the Education Committee, said school closures were "a national disaster for children in terms of their learning loss, their mental health, a rise in their safeguarding risks and damage to their life chances".
He warned that there were real questions about whether the Government catch-up offer "is actually working".
In a new report, MPs pointed to studies showing a fifth of pupils did no schoolwork at home or less than an hour a day during the pandemic - and absence remains high now schools have reopened, with 182,000 pupils out of class for Covid-related reasons on February 10.
It comes after Children's Commissioner Dame Rachel de Souza warned this week that nearly 1.8 million pupils had missed at least 10% of school last autumn.
The committee demanded action to ensure that no more pupils became "ghost children" - those who have fallen off of schools' radars during the pandemic.
Disadvantaged pupils could be up to eight months behind their peers in the worst case scenarios, while progress made towards narrowing the attainment gap has stalled.
The report underlined significant regional inequalities, with primary pupils in Yorkshire and the Humber 5.3 months behind on maths compared to just 0.5 months in the South-West.
MPs said the Government's flagship National Tutoring Programme appears to be "failing the most disadvantaged", with the scheme reaching 100% of its target schools in south-west England but just 58.8% in the North East by March 2021.
Ministers were challenged to prove the scheme was working - or scrap the multi-million pound contract with provider Randstad.
The tutoring scheme, which has faced criticism in recent days, has so far reached just 15% of its overall target, the report said.
The committee said it is "not clear that the National Tutoring Programme will deliver for the pupils that need it most" and that there needs to be full transparency over how the scheme is working.
Children are facing a "mental health crisis" which has been exacerbated by the pandemic, the report said.
Around one in six children aged between six and 16 have a probable mental health disorder, with witnesses telling the committee that one of the biggest issues for pupils' mental wellbeing is their access to social media.
It also criticised a "spaghetti junction" of catch-up funding, with £5 billion of recovery spending announced by Government since June 2020, and headteachers raising concerns about the "complication" of accessing funds.
Mr Halfon said catch-up funding is "not reaching the most disadvantaged children", while "there are significant regional disparities and there is a real risk of failure through Randstad as the delivery partner".
"Moreover, it is not reaching the hundreds of thousands of 'ghost children' who have not returned to school," he said.
"Given the increase in children's mental health problems, more work needs to be done to rocket-boost support."
He concluded: "The Government must ensure Randstad shapes up, or boot them out. The catch-up programme must be shown to be reaching disadvantaged pupils and this data must be published."
Dr Mary Bousted, Joint General Secretary of the National Education Union, said: "This is a serious warning from the Education Committee that if government doesn’t provide enough support for disadvantaged young people, they risk baking in the deepening inequalities between disadvantaged children and their better off peers."
Nick Brook, deputy general secretary of school leaders’ union NAHT, said: "Well before the pandemic hit, the gap in attainment between children from wealthy and poor families had stopped closing.
"Nearly 18 months of progress already separated pupils from the poorest communities from their more affluent peers. As this report powerfully highlights, an already bad situation will have been made all the worse by the impact of Covid."
A Department for Education spokesperson said: "Tutoring plays an integral role in supporting pupils to catch up on any lost learning and delivery is on track to meet the ambitious target of teaching two million courses this academic year.
"We continue to work with Randstad to ensure as many children from all backgrounds - in particular those from disadvantaged backgrounds - across the country can benefit from high quality tutoring and catch up on lost learning."
Karen Guthrie, senior programme director of the National Tutoring Programme, said: "The Education Select Committee report is right to focus attention on the National Tutoring Programme and the important role it plays delivering education catch up to pupils whose education has been most impacted by the pandemic. We are working closely with schools across the country who are best placed to select pupils that need tuition the most.
"We have been working in partnership with the Department for Education, schools and tuition partners to look at how we can improve the Programme moving forward to best serve the needs of schools.
"We receive regular feedback from schools and as the Programme evolves want to offer the greatest flexibility to Tuition Partners while removing complexity from the Programme - we want to encourage schools to consider all three tuition routes to best match their needs."
