Britain's broadcasting watchdog has signalled it may move against the Kremlin TV station showing the Alex Salmond Show.

Ofcom has announced it will speed up a probe in to whether RT, the former Russia Today, is"fit and proper".

The regulator added that any finding that the Russian state was most likely behind the poisonings in Salisbury of a former spy and his daughter would be "relevant" to this investigation.

Its remarks come as pressure mounted on an increasingly isolated Mr Salmond as SNP figures lined up to criticise RT and other outlets deemed by Nato, the EU and the UK to be propaganda and misinformation vehicles.

READ MORE: Alex Salmond branded Putin's "useful idiot" as political pressure piles on ex-FM to quit RT show

A Liberal Democrat MSP called Mr Salmond a "useful idiot" - a term for those who unwittingly supported the Soviet regime - and urged him to quit RT.

The former First Minister himself, however, showed no sign of leaving the Russian station, where he is the highest profile UK figure.  Mr Salmond said: "I shall be addressing the developing crisis on Thursday, so watch the Show to find out what I think." 

Ofcom said: "As the independent UK broadcasting regulator, Ofcom has an ongoing duty to be satisfied that broadcast licensees remain fit and proper to hold their licences.

"We have today written to ANO TV Novosti, holder of RT’s UK broadcast licences, which is financed from the budget of the Russian Federation.

"This letter explained that, should the UK investigating authorities determine that there was an unlawful use of force by the Russian State against the UK, we would consider this relevant to our ongoing duty to be satisfied that RT is fit and proper.

"The letter to RT said that we would carry out our independent fit and proper assessment on an expedited basis, and we would write to RT again shortly setting out details of our process."

RT denied anything had happened since the Salisbury poisonings to justify a review of its licencing.

In a statement issued through a PR agency, it said: “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. "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 Salmond had been a regular on the RT before doing his show

There has been some political support for an outright ban on RT and its sister organisation, Sputnik. Some Kremlin-watchers, however, have cautioned against such a move amid fears of a tit-for-tat retaliation against UK free press or broadcasters in Russia.

BACKGROUND: Why the mainstream SNP is worried about Russian propaganda

Ben Nimmo, a fellow with the Atlantic Council's Digital Forensic Research Lab, responded to speculation of an RT ban said: "Anyone want to bet whether the Russian government would welcome the excuse to silence the BBC Russian service just before the elections this weekend?"

Last week the SNP renewed its attacks on RT but its MP Martin Docherty cautioned against taking the channel off the air, saying: "Simply, banning RT would have little effect on its already small viewership, and would lead to the potential for tit-for-tat actions against organisations like Radio Liberty or the BBC Russian service, which provide vital services to people living under Putin’s authoritarian regime."

SNP leaders have recently avoided targetting Mr Salmond for personal criticism, despite an unprecedented initial reaction to his deal with RT. Alyn Smith MEP, in a highly unusual on-the-record comment, responded to news of the Alex Salmond Show by saying "What the f**k was he thinking?"

Scottish Liberal Democrat MSP Alex Cole-Hamilton, on Tuesday said: “Alex Salmond needs to end his relationship with Russia Today.

“In the space of a week we’ve seen Vladimir Putin fan anti-Semitism by blaming US election meddling on the Russian Jewish community and the nerve agent used in a murder plot on British soil traced back to Russian labs.”

READ MORE: Alex Salmond branded Putin's "useful idiot" as political pressure piles on ex-FM to quit RT show

Mr Cole-Hamilton said that the former SNP leader had claimed editorial control of his show, which meant he should condemn the latest developments.

He added: “Salmond has played the useful [and well paid] idiot in RT’s veneer of respectability for long enough.”

Harold Elletson, a Russia expert and former Conservative MP, said Mr Salmond “wouldn’t have a leg to stand on” if he remained at RT.

He told The Times that the channel was “a propaganda instrument of the Russian state, at a time when Russia was engaged in a very aggressive information campaign, if not an information war, against the West. That puts Salmond in an extremely difficult position.”

He added: “Sometimes the truth is more important than the paycheck.”