Britain has accused Russia of creating “fantasies” around the nerve agent attack in Salisbury as the broadcasting watchdog investigates its state broadcaster over impartiality.

Ofcom has opened seven probes into news and current affairs shows including two hosted by former MP George Galloway on Russia Today (RT), which is owned by state media arm TV Novosti.

A spokesperson for the watchdog said: “Until recently, TV Novosti’s overall compliance record has not been materially out of line with other broadcasters.

“However, since the events in Salisbury, we have observed a significant increase in the number of programmes on the RT service that warrant investigation as potential breaches of the Ofcom Broadcasting Code.”

The announcement came as the UK accused Russia of proposing “contradictory and changing fantasies” to deny involvement in the attack on former double agent Sergei Skripal.

Peter Wilson, Britain’s permanent representative to the Organisation for the Prohibition of Chemical Weapons (OPCW), told a meeting of the body’s executive council a “brazen disinformation campaign” was underway.

“They have sought to confuse, distract and brazenly misrepresent facts, despite the thorough, independent OPCW report” that confirmed novichok nerve agent was used, he said.

“To date, Russia has proposed more than 30 contradictory and changing fantasies to explain the Salisbury attack. Russia’s actions to confuse and distract have not worked, but instead show how hard they are working to hide the truth.”

Ofcom’s code states that all news must be reported “with due accuracy and presented with due impartiality”, and that “undue prominence” must not be given to a particular side on matters of controversy.

Ofcom said it would announce the outcome of investigations as soon as possible and consider all relevant new evidence alongside RT’s future conduct.

RT has an average audience of 3,400 viewers at any given point during the day and an average weekly reach of 1 per cent of UK adults, according to Ofcom figures.

Owner TV Novosti has been disciplined for 15 breaches of the broadcasting code since 2012, which Ofcom said was not an unusually high number, but most related to Russia’s foreign policy in programmes on the wars in Libya, Syria and Ukraine.

All programmes being currently considered were broadcast after Mr Skripal and his daughter Yulia were poisoned with a nerve agent in Salisbury on 4 March.

They include editions of the Sputnik programme, which is presented by Mr Galloway and his wife Gayatri and claims to “go behind the stories which made the news” with “authoritative and influential” guests.

The two shows in question both discussed the Salisbury attack were broadcast on 17 March, featuring an “independent researcher”, and 7 April, which included Russian commentator Alexander Nekrassov.

Two RT news broadcasts on 18 and 30 March are also being investigated over due impartiality, alongside two editions of the flagship programme Crosstalk, which discussed alleged chemical weapons attacks in Syria on 13 and 16 April, and Worlds Apart with Oksana Boyko on 1 April, which featured an interview with the father of murdered former Russian spy Alexander Litvinenko.

Ofcom noted that several state-funded outlets operate in the UK, including Qatar’s Al Jazeera network and the BBC itself, but said it did not consider actions outside of broadcasting when ruling on licences in order to protect diversity and freedom of expression.

“States sometimes commit, or will have committed, acts which are contrary to UK and generally accepted values,” a spokesperson said. 

“In our judgment, it would be inappropriate for Ofcom always to place decisive weight on such matters in determining whether state-funded broadcasters were fit and proper to hold broadcast licences.”

Ofcom stressed that it was not seeking to pass judgement on the attack in Salisbury itself, which the government has attributed to Russia despite Kremlin denials.

“We disagree with the position taken by Ofcom; our broadcasting has in no way changed this week from any other week, and continues to adhere to all standards,” a spokesperson for RT said.

“By linking RT to unrelated matters, Ofcom is conflating its role as a broadcasting regulator with matters of state. RT remains a valuable voice in the UK news landscape, covering vital yet neglected stories and voices, including those of the many MPs and other UK public figures who have been shut out of public discourse by the mainstream media.”

Mr Galloway has not yet responded to The Independent’s request for comment.

Britain and its allies have expelled Russian diplomats over the Salisbury incident, which sparked an escalating diplomatic row that heightened further following an alleged chemical attack in Syria and airstrikes against Bashar al-Assad’s forces.

On Tuesday, officials announced the start of decontamination work in Salisbury at nine sites including Mr Skripal’s house, the restaurant and pub he visited with his daughter and areas used by emergency services.

The operation will involve around 200 military personnel and is expected to take several months.

Mr Skripal remains in hospital, where his condition has improved, while his 33-year-old daughter was discharged earlier this month.