The British government was forced Monday to abandon its policy for grading exams that were cancelled because of the coronavirus pandemic after protests by students and warnings that it threatened the career prospects of the most disadvantaged pupils.

England's exam regulator said it would accept at face value assessments made by teachers in lieu of high school exams, abandoning a moderation process intended to avoid widespread grade inflation.

The publication of A-level results last week sparked outrage when it emerged that 39 percent of teachers' assessments had been downgraded under an algorithm based on a school's past performance.

A-levels are key school-leaving exams for 18-year-olds.

Pupils took to the streets and threatened legal action, complaining the system made it harder for bright children in disadvantaged areas to do well, while rewarding mediocre students in private schools.

"To a lot of young people this really does feel like the government is saying 'we don't care about you'," 18-year-old Curtis Parfitt-Ford, who launched a petition and a legal challenge against the policy, told AFP.

As angry parents lobbied their MPs, opposition parties scented an opportunity, and increasing numbers of Prime Minister Boris Johnson's Conservative party called for a rethink.

The devolved governments in Scotland and Wales had already reverted to teachers' assessments, putting pressure on England to follow suit -- particularly with another key set of results, for GCSEs taken by 16-year-olds, due on Thursday.

Teachers had also raised concerns that schools would be tied up lodging appeals against results when they were trying to prepare to reopen fully in early September for the first time since the March lockdown.

Johnson's Education Secretary Gavin Williamson apologised for the handling of the process, saying he had decided to act after "unfairnesses" became clear.

"I am sorry for the distress this has caused young people and their parents but hope this announcement will now provide the certainty and reassurance they deserve."

The devolved government in Northern Ireland later announced it would also change its policy.

'Desperately unfair' 

Johnson has been widely criticised for his government's response to coronavirus, which has left 41,000 people dead in Britain -- the highest toll in Europe.

Despite complaints over the late imposition of a lockdown, a lack of testing and protective equipment, his Conservatives remain favoured in opinion polls.

But former Tory leader Ruth Davidson noted the exams chaos "is not just one of these bubble issues. This is something that cuts through everything" -- and many MPs agreed.

More than 250,000 people had also signed a petition demanding a change, and two legal groups representing students threatened to take the government to court.

The director of one of them, Good Law Project's Jolyon Maugham, said pupils had missed out on places at university, medical school and employer training, which all rely on final A-level grades.

"It's also affecting those students who are leaving school to enter the jobs market, the most difficult jobs market in the UK for many generations," he told AFP.

He added: "That's desperately, desperately unfair."

'Complete fiasco' 

The leader of the main opposition Labour party, Keir Starmer, welcomed the "screeching U-turn".

"This is a victory for the thousands of young people who have powerfully made their voices heard this past week," he said.

"However, the Tories' handling of this situation has been a complete fiasco. Incompetence has become this government's watchword."

Like in many countries hit by COVID-19, exams in Britain in April, May and June had to be abandoned because of the pandemic.

Teachers were asked instead to make an assessment of their students' grades, which were then modified based on a school's past performance.

Despite the high percentage of results downgraded, the number of pupils in England, Wales and Northern Ireland receiving the highest A-level grades increased.

Under the new policy, students whose results were moderated upwards will be able to keep those grades.