The government has reversed policy on wearing facemasks in schools in England, sparking fresh criticism about its handling of the coronavirus outbreak.

Ministers had insisted face coverings were not necessary when children go back to school from next week after nearly six months out of the classroom amid concern about a rise in infections.

But in new guidance late Tuesday, the British government advised that secondary school students and staff should wear face coverings in corridors and communal areas.

The change is being seen as another  U-turn, just weeks after ministers were forced to scrap the use of an algorithm which gave 17- and 18-year-olds lower-than-expected exam grades.

Teaching unions have been calling for English schools to follow guidance in Scotland, which has a separate education system, that requires pupils to cover their nose and mouth between lessons.

But while welcoming the change, critics including the main opposition Labour party said ministers had shirked their responsibility by leaving enforcement to individual schools.

Labour's education spokeswoman Kate Green slammed a "half-baked U-turn". "The government should have given clear guidance and a plan to deliver it," she said.

Under-fire Education Secretary Gavin Williamson had insisted masks were not required in schools and Prime Minister Boris Johnson's office said there was no plan to review the policy.

But Williamson, widely blamed for the furore over exam results, on Wednesday said the government would now follow World Health Organization advice for children aged 12 and over to wear masks.

"Outside of local lockdown areas face coverings won't be required in schools, though schools will have the flexibility to introduce measures if they believe it is right in their specific circumstances," he said on Wednesday.

"I hope these steps will provide parents, pupils and teachers with further reassurance."

Some 41,500 people have died in the coronavirus outbreak in Britain -- the worst death toll in Europe -- and the government response to the pandemic has been criticised.

Ministers were accused of not reacting quickly enough, failing to ensure enough protective equipment for frontline health and social care workers, and over the testing regime.

London reversed policy on the wearing of facemasks in shops in England after initially saying they were not necessary, and was forced to backtrack on a planned reopening of primary schools in July. 

Education is a devolved issue for regional governments in Scotland, Wales and Northern Ireland.

Older students in Northern Ireland will be asked to wear face coverings outside classrooms from next week. The Welsh Assembly in Cardiff is due to make its decision on Wednesday.