Boris Johnson says fans who booed England players taking the knee before games should get behind the team and "cheer them".
Players taking the knee in protest against racial injustice prior to two friendly matches in Middlesbrough were met with boos from a section of the home crowd at the Riverside.
A No 10 spokesman said on Friday that the Prime Minister wants the public to “cheer them on, not boo” and explicitly supported those who decide to take part in the protest.
The Prime Minister’s official spokesman earlier this week declined to condemn those who booed players, only going so far as urging them to be “respectful”.
But Downing Street has now gone further to tell crowds not to jeer the national team after coming under pressure to take a firmer stance.
Asked if Mr Johnson backs players taking the knee, the No 10 spokesman said: “Yes. The Prime Minister respects the right of all people to peacefully protest and make their feelings known about injustices.
“The Prime Minister wants to see everybody getting behind the team to cheer them on, not boo.”
It later emerged that Scotland players will take the knee in solidarity with their England counterparts when they meet at Wembley.
The Scots had confirmed on Thursday they would continue standing together in opposition to racism before their European Championship games.
But the reaction to their decision – both negative and positive – has prompted a partial rethink 24 hours later.
Scotland will still stand before their Hampden Park games but make an exception for their Auld Enemy encounter in London on June 18 as a gesture of togetherness with their opponents, who were booed by some of their own fans when they kneeled ahead of two warm-up games at the Riverside Stadium in Middlesbrough.
Head coach Steve Clarke felt their announcement that they would stand against racism had been “politicised or misrepresented” in some quarters.
“In light of divisive and inaccurate comments being perpetuated by individuals and groups, whose views we denounce in the strongest terms, we have reflected today as a group,” Clarke said.
“We will continue to take a stand – together, as one – for our matches at Hampden Park. For our match at Wembley, we will stand against racism and kneel against ignorance.”