Another UK council has defied the Government by refusing to reopen schools on June 1.
Leaders in Hartlepool have joined those in Liverpool by rejecting the plans which unions have slammed as putting teachers and children at risk.
Union chiefs have accused ministers of going too fast and want more local control over the return of schoolchildren.
In a statement, Hartlepool Council said: "Given that coronavirus cases locally continue to rise, Hartlepool Council has been working with schools and we have agreed they will not reopen on Monday 1 June.
"Whilst we recognise the importance of schools reopening, we want to be absolutely clear that we will be taking a measured and cautious approach to this.
"We continue to work with schools to put in place appropriate measures to help keep children and staff safe when a phased reopening is possible."
Patrick Roach, general secretary of union NASUWT, yesterday said it would take legal action against head teachers if schools re-opened without proper protections for staff.
But in an extraordinary turn, former Education Secretary David Blunkett has accused the unions of "working against the interests of children".
And Sir Anthony Seldon, Vice-Chancellor of the University of Buckingham and ex-head of Wellington College, said: "Teachers want to and need to be back in schools.
"As long as the scientists say they can, it is utterly wrong for unions to try to block and discourage teachers."
While current Education Secretary Gavin Williamson has urged the unions to do their "duty" and halt any opposition to getting children back behind their desks despite the pandemic.
Writing for the Daily Mail, he said returning kids to school is "in the interests of their welfare and education".
In Liverpool, city leaders said it was more likely school would not return until mid-June- and children of key workers would return first.
In a letter to parents, Liverpool council's director for children and young people's services Steve Reddy warned: “There is no doubt in my mind that we simply cannot reopen schools in line with the suggested timetable outlined by the government.
"The layout of every school is different and they all have different challenges to overcome in terms of maintaining social distancing and hygiene."
Liverpool Mayor Joe Anderson warned earlier this week that he would resist sending kids back at the beginning of next month, saying he had concerns about whether schools would be able to operate safely.
He told BBC Newsnight: “I’m not going to take risks with children’s lives or with staff and teaching professionals' lives.”
The city council's decision comes after Wales, Scotland and Northern Ireland, also split from the government's schools timeline.
England is the only part of the UK asking schools to begin phased reopenings from the start of next month.
Schools in Wales will not open on June 1, First Minister Mark Drakeford earlier confirmed.
Prime Minister Boris Johnson set out plans to encourage the UK get back to normal after the coronavirus lockdown.
One of the measures was to partially bring children back into primary schools, from Reception, Year 1 and Year 6.
The Department for Education said that kids would be kept apart in small groups, regular hand washing would be encouraged, and those with coronavirus symptoms would be asked not to go into school.
But teaching unions have rejected the plans, saying teachers and children would be at risk of catching the disease and accelerating its spread back out in the community.
In the North-east the 'R' transmission rate is the highest in the country at around 0.8 - in London, the initial epicentre of the outbreak, it's 0.4.
On Friday, education unions were invited to a meeting with Government ministers and scientists about their plan.
But union leader Dr Roach said the meeting "has raised more questions than answers".
He said the evidence to reopen on June 1 was "weak" and no new evidence had been provided.
"No confirmation was provided that teachers are at low risk of catching the virus following the wider opening of schools," he said.
"No clear information was provided on what modelling has been undertaken in relation to potential transmission rates when schools open more widely.
"Nothing in the meeting provided reassurance for the deeply worried and anxious school workforce.
"We are continuing to press for answers to these questions and also for clear guidance from Government to schools to ensure that they take appropriate and reasonable steps to assess and mitigate the health and safety risks posed by Covid-19."
Other Teesside councils have yet to make announcements about their plans.
Jacob Young, Tory MP for Redcar, said he and fellow Conservative MP Simon Clarke had spoken to headteachers across Redcar and Cleveland on Friday.
He heaped praise on the response of schools and leaders for their work in looking after vulnerable kids and those of key workers during the pandemic.
"They’re now starting to prepare for schools to begin to reopen in a few weeks time, and we will obviously approach with caution," Mr Young said.
"The aim is that from early June - Reception, Year 1 and Year 6, will start to go back into school. But this will only happen if we can prove that the risk of infection is lower than it is today.
"We will not take any steps that puts children or staff at risk - and all children and staff, who are showing symptoms of coronavirus, are eligible for a coronavirus Test."
