Boris Johnson has stepped up his call for parents to send their children back to school in September as the Government warned they could be fined if they failed to do so.

The Prime Minister said it was “absolutely vital” that England’s schoolchildren returned to the classroom and there was only a “very, very, very small” chance of them contracting coronavirus.

Ministers stressed that it would be compulsory for children to attend school, with fines being used as a “last resort” to punish parents who did not comply.

The Government has repeatedly said that schools will be the last thing to shut if there are local lockdowns and Downing Street said that if that happened, teachers would be expected to continue classes remotely.

The Prime Minister said a return to class in September was essential for children’s education and wellbeing.

He acknowledged that parents “are genuinely still a bit worried” about their children contracting coronavirus.

“All I can say is the risks are very, very, very small that they’ll even get it, but then the risk that they’ll suffer from it badly are very, very, very, very small indeed,” he said.

“I think it’s vital that parents understand that schools are safe and that teachers have gone to great lengths to get schools ready.”

Schools standards minister Nick Gibb said if parents had concerns they should raise them with head teachers, but stressed that attendance was not optional for children.

“We live in a country where education is compulsory and I think parents can be reassured that the measures that schools are taking to make sure that we minimise the risk of the transmission of the virus are very effective,” he told BBC Radio 4’s Today programme.

Local authorities can fine parents £120 – cut to £60 if paid within 21 days – over a child’s absence from school, with the threat of prosecution if they fail to pay.

Mr Gibb said it was a “moral imperative” for children to go back to school.

As schools prepared to fully reopen in England:

– Downing Street said there were no plans to review guidance on whether pupils and teachers should wear masks.

– The Scottish Government is consulting on whether secondary school pupils and staff should wear face coverings when moving around schools.

– Schools began the process of reopening in Northern Ireland.

– The NHS Test and Trace system has faced fresh criticism for a flaw in its online booking system which tries to direct people to test centres more than 100 miles away.

– The first case of someone being reinfected with coronavirus has been reported by researchers in Hong Kong.

The task of getting children to return to classrooms comes with Mr Johnson and Education Secretary Gavin Williamson under pressure following the fiasco over A-level grades.

Downing Street said the Prime Minister is “sorry for any distress” caused by the way grades were awarded after the cancellation of GCSE and A-level exams – initially using an algorithm but then, following a U-turn, based on teachers’ assessments.

“The PM is of course sorry for any distress that has been caused,” a Number 10 spokesman said.

“Our focus has been and will be ensuring that students can move on to the next phase and ensuring kids can get back to school next week.”