Senior Labour figures and the family of former party leader Michael Foot have reacted with anger over the re-emergence of the explosive claim that he was a paid Soviet informant.

Neil Kinnock, who succeeded Foot as Labour leader, said his predecessor had been a “passionate and continual critic of the Soviet Union” in response to the allegation that MI6 believed Foot had been a paid informant.

Labour’s current leader, Jeremy Corbyn, the shadow chancellor, John McDonnell, and Foot’s descendants were among those to condemn the publication of the claims eight years after his death. Foot successfully sued the Sunday Times when it published similar allegations 23 years ago.

The story comes as Britain’s relationship with Moscow is yet again at a low ebb after two Russian nationals were charged over the poisoning of Sergei and Yulia Skripal in Salisbury, Wiltshire. The pair have since said they were in the city to visit its cathedral.

The original allegations about Foot date back to the claims of Soviet defector Oleg Gordievsky, who alleged that the former Labour leader had received clandestine payments from the KGB and had been classed by the organisation as an “agent” and “confidential contact”.

The fresh claim appears in a new book, The Spy and the Traitor, by the Times writer Ben Macintyre and also featured on the newspaper’s front page on Saturday.

Kinnock said Foot had always been an opponent of the Soviet Union’s “internal and external despotism”.

“He would never have served their purposes,” he said. “When these allegations were made against him in 1995 he sued the Sunday Times and won substantial damages. He has been dead for eight years. Repeating such claims without any substantive additional proof is filthy.”

McDonnell told the Observer: “Michael Foot was a good and honest socialist whose only desire was to serve our country. Elements of the British media are sinking to new lows in debasing standards of journalism in this country. They used to be called the gutter press. Now they inhabit the sewers.”

Corbyn tweeted on Saturday:

Michael Foot loved this country. That's why he wanted to make it better for everyone.



Smearing a dead man, who successfully defended himself when he was alive, is about as low as you can go. — Jeremy Corbyn (@jeremycorbyn) September 15, 2018

John Foot, a great nephew of the former Labour leader, tweeted: “My great-uncle Michael Foot was a lifelong anti-Stalinist. Friend of Orwell ... Ludicrous to claim he was a Soviet spy. Sued successfully for libel around this when he was alive. No evidence. Shameful and cowardly.”

Chris Mullin, the former Labour minister who worked with Foot, said he believed the claim was “cowardly ... given that Michael Foot is in no position to answer back”, adding: “He was a good, honourable man and a democrat to his fingertips.”

Macintyre’s new book states that MI6 agents had been told about Gordievsky’s claims in the summer of 1982. It also says they concluded that Foot had not been a “spy or conscious agent”, but had been used for “disinformation purposes” and received the equivalent of £37,000 in today’s money.

It says that they were prepared to warn the Queen, should Labour have won the election in 1983. “Within MI6 there were discussions about the constitutional implications if Michael Foot won the election,” it states. “It was agreed that should a politician with a KGB history become prime minister of Britain, then the Queen would have to be informed.”

The Times’ coverage of the story suggests that, had the new revelations been known at the time that the allegations first emerged, “it is unlikely Foot would have resorted to the libel courts”.