Moscow has threatened to ban all British media from Russia if its state-backed television network RT is pulled off the airwaves in the UK.

Maria Zakharova, a spokesperson for the Russian foreign ministry, said Tuesday during a television appearance that "no British media will work in our country if they close Russia Today."

The threat is a sign of escalating tensions between London and Moscow after Prime Minister Theresa May said Monday that a nerve agent developed by Russia had been used in the attempted murder of a former double agent, Sergei Skripal.

The British government has demanded an explanation from the Kremlin.

UK media regulator Ofcom has said it would consider whether RT was "fit and proper" to hold a broadcast license once the government had more information.

The regulator said Tuesday that it had warned RT that it would "carry out our independent fit and proper assessment on an expedited basis" if UK authorities conclude that Russia was behind the attack.

Some lawmakers told May on Monday they were concerned that the network, which also uses the name Russia Today, was functioning as a propaganda outlet.

May did not address the issue directly in a statement to parliament, but acknowledged that "Russia Today is of concern to members across the House [of Commons]."

RT said it was being sacrificed as a political pawn, "in one fell swoop doing away with any concept of press freedom in the UK."

"We are proud to have a better record with Ofcom than most other UK broadcasters, and any curtailment of RT will ultimately be to the detriment of the British public," RT said in its statement.

"By linking RT to unrelated matters, Ofcom is conflating its role as a broadcasting regulator with matters of state," it added.

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RT is owned by Russian state-owned news agency RIA Novosti. RT's UK broadcast licenses were granted to the company's television division, ANO TV Novosti.

RT has a very small viewership in the UK, but members of parliament have frequently appeared on the channel. The former Scottish leader Alex Salmond hosts a show on the network.

Ofcom has revoked 10 broadcasting licenses since 2003. The most recent was in 2017, when a radio station was pulled off the air for broadcasting hate speech.

The regulator pulled the license of the English-language news network of Iranian state broadcaster Press TV in 2012.

The BBC and other media outlets including The Guardian could be affected if British media are not allowed to operate in Russia.

-- CNN's Sebastian Shukla contributed reporting.