The Government must resist pressure from unions over face masks in the classroom, former ministers and parents have said.
Boris Johnson has been told not to "pander" to teaching union bosses who have demanded that children should continue to wear masks during lessons until at least June 21.
Three former Department for Education (DfE) ministers have urged the Government to keep its promise to remove the requirement on May 17, when step three of the roadmap out of restrictions is due to come into effect.
The Tory MP Tim Loughton, a former children's minister, said masks in the classroom should be dropped "as a matter of urgency".
He added: "At every step of the way, the National Education Union seems to have been at the vanguard of making it more difficult for children to be taught in classrooms and at every step they have made the wrong calls."
Robert Halfon, the Conservative chair of the education select committee and a former DfE minister, said the Government must stick to May 17 as the date for ending masks in the classroom "like super glue".
He told The Telegraph: "If the rest of society is opening up, it seems absolutely clear that the face masks need to go on this day and particularly given the low Covid rate among children."
Chris Skidmore, a Tory MP and DfE minister until last year, said the "blanket national policy" for children to wear face masks in lessons should be removed on May 17 and only used in situations such as containing a local outbreak.
The former Tory party leader Iain Duncan Smith also called for face masks to be dropped in lessons, adding: "The evidence now from all the schools is that there have been no more infections than in the rest of society."
Their interventions come after several unions – including the NEU, NASUWT, Unite, Unison and GMB – wrote to the Education Secretary, Gavin Williamson, claiming that face coverings are "essential" for Covid prevention in schools and should continue to be required until at least the penultimate week of June.
Mr Johnson announced in February that secondary pupils would need to wear face masks anywhere indoors where they could not socially distance, including in the classroom as well as in corridors when they returned to school on March 8.
At the time he said it was a temporary measure and would be reviewed by Easter – but it was then extended until May 17 at the earliest.
Molly Kingsley, a co-founder of the parent campaign group UsForThem, said: "The Government’s duty is to children, not unions. They must not keep pandering to unions that don't have pupils' interests at heart."