The plan for all primary school years in England to go back to school before the end of term is to be dropped by the government.
There was an aim for all primary pupils to spend four weeks in school before the summer break.
But it is no longer thought to be feasible – and instead schools will be given “flexibility” over whether or not to admit more pupils.
Head teachers’ leaders said it had never been a practical possibility.
It comes after Health Secretary Matt Hancock conceded at Monday’s Downing Street briefing that secondary schools in England may not fully reopen until September “at the earliest”.
There are separate rules for managing the threat of coronavirus in England, Wales, Scotland and Northern Ireland.
Children in England began returning to primary schools in a phased process last week, with Reception, Year 1 and Year 6 pupils heading back first.