THE editor of the Edinburgh-based news agency widely believed to be a mouthpiece for Russian President Vladimir Putin has admitted his station has a “reputation problem”.

However Egor Piskunov, who has defended Sputnik UK's journalism, proceeded to take the Kremlin line on the Skripal nerve agent attack by casting doubt on his country’s involvement in the attempted murders.

He also said he was “not convinced” Russia was behind the assassination on UK soil of another spy, Alexander Litvinenko, despite a public inquiry concluding that Putin had “probably” approved the hit.

Scottish Conservative chief whip Maurice Golden described Sputnik as "a biased, propaganda outlet run by amateurs. No proper consumer of news and information could possibly take it seriously.”

The Skripal case has led for calls for a crackdown on UK-based media organisations that are funded by Russia.

Sputnik UK is a news website platform and radio broadcast service headquartered in Edinburgh. However, it is regarded as a propaganda platform for the Kremlin.

In an interview with the Sunday Herald, Piskunov, Sputnik UK’s editor in chief, said the “mainstream” media coverage of the poisoning had been a “bit one-sided” and said there was “no evidence really” of Russian involvement.

He said: “I do think some important details are often not really being reported as widely as I think they should be.”

Echoing a social media conspiracy theory, he flagged up the presence of a military lab in Porton Down, near Salisbury.

Asked whether it was more likely than not that Russia was behind the attacks, he said: “I think that the link which Russia is being connected to the story with [a Soviet produced chemical] not enough to make these accusations.”

Piskunov, who also worked for Russian broadcaster RT, added: “The formula of this chemical was published in a book in the United States – everybody has access to that.”

Asked if he was convinced that former Russian spy Litvinenko had been murdered by actors of the Russian state using radioactive polonium in London in 2006, Piskunov said: “I am not convinced.”

On whether Sputnik has a reputation problem, he said: “Sputnik does have a reputation problem and we are trying to fix it.

“The problem is that there’s a general trend in linking Russian publicly-sponsored media directly to the Kremlin.”

Asked if Sputnik carries out investigations into Putin’s presidency, he replied: “For us here in Sputnik UK, it would be very hard to do any of these investigations. I don’t really see how that would really fit with our format.”

Asked if he had any criticisms of Putin, he said: “By representing the whole spectrum of opinions, that’s our balance. That’s how we remain sort of neutral.”

Liberal Democrat MSP Alex Cole-Hamilton said: “Organisations such as Sputnik pump out Putin-backed propaganda and have been complicit in the cover up of events from human rights breaches to the Russian invasion of Crimea.

“I have filed a motion in the Scottish Parliament urging all groups and individuals in Scottish public life to take a stand by refusing future invitations for interview and to end any commercial relationships with Russian state backed media outlets immediately. I would like to see MSPs from across the Parliament make this commitment.”