Ministers set for showdown with schools as hundreds could stay shut on June 1
Some councils have told schools they do not have to reopen
As many as 1,500 English primary schools could refuse to reopen on 1 June amid a growing backlash over the Government's plans.
The Guardian reports that at least 18 councils have told schools they would not be forced to open at the beginning of next month as they expressed safety concerns or warned they would not be ready in time.
It comes after ministers said children in Reception, Year 1 and Year 6 in England would be able to return to school on 1 June if infection rates continue to fall, insisting the plans were based on the "best scientific and medical advice".
But councils in Bury, Liverpool and Hartlepool have already advised schools not to reopen due to uncertainty over the risk of transmitting the virus.
Meanwhile, Conservative-led Solihull Council also warned some schools in the area would be not be ready to resume teaching by the beginning of June.
The move comes after Education Secretary Gavin Williamson held further meetings with union leaders in an effort to reassure them the plans would not see children or teachers put at risk from the virus.
But teaching union NASUWT said they remained "unconvinced" the plans were "appropriate and practicable".
And they said a survey of 29,000 of their members had found just one in 20 believed it would be safe for children to return to schools next month.
The backlash from councils follows reports that ministers were considering legal action against those who refused to comply with the order, but a Number 10 spokesperson insisted talks would continue in a "consultative way".
They added: "You can see what the focus of our attention is at the moment, which is trying to work with them in a consultative way in order to be able to open schools to more pupils in a way that is safe."
Meanwhile, the Government's plans were dealt a further blow on Tuesday after deputy chief scientific adviser Dame Angela McLean said any further relaxtion of the lockdown should only come after the track and trace scheme was in place.
Speaking at the daily Downing Street press conference, she said any changes to the rules should be based on "observed levels of infection... and not on a fixed date".