BBC journalist Sarah Rainsford has left Russia after the government abruptly refused to extend her permission to work in a tit-for-tat row with Britain over the treatment of foreign media.

Russian authorities earlier this month told Ms Rainsford, one of the BBC's two English-language Moscow correspondents, to leave the country in retaliation for what it called London's discrimination against Russian journalists working in Britain.

Russian authorities accused the UK government of mistreating a Russian journalist working for the state TASS news agency in London who they said was forced to leave in 2019 after his visa was not extended without explanation.

They said they had tried and failed to get Britain to remedy the situation before deciding to retaliate in kind.

The BBC has called the expulsion of Ms Rainsford a "direct assault on media freedom" and the British government had without success urged Russian authorities to reconsider their decision.

Ms Rainsford, who has said she was devastated by the move, posted pictures on Twitter from a Moscow airport before she boarded a flight out of the country.

"I have to leave Russia," she wrote.

Russia's foreign ministry has made clear it will not allow the BBC to send her back or replace her with someone else until Britain gives a visa to a Russian state journalist.