FORMER Labour leader Michael Foot was a paid KGB “informant” and spooks planned to warn the Queen if the party came to power, a new book claims.

MI6 believed Foot, who died in 2010 aged 96, had received money from the Soviet Union in the 1940s and was later used by spies for spreading “disinformation”.

They didn’t step in before the 1983 election because the information was seen as “far too politically incendiary” and could have swayed the result.

The claims first came to light after the 1982 defection of Oleg Gordievsky, the subject of a new book by The Times journalist Ben Macintyre.

Although MI6 did not think Foot was a “spy or conscious agent”, it accepted Gordievsky’s claim he was classed by the Soviets as an “agent” and “confidential contact”.

The Times is serialising the book, which features interviews with former secret service officers.

It says: “Within MI6 there were discussions about the constitutional implications if Michael Foot won the election.

“It was agreed that should a politician with a KGB history become prime minister of Britain, then the Queen would have to be informed.”

Foot successfully sued The Sunday Times in 1995 when it published claims by Gordievsky that the KGB held an extensive file on him, and had nicknamed him “Agent Boot”.

He called the allegations a “big lie” and said he had never met or seen a KGB agent in his life.

But The Spy and the Traitor says Gordievsky told his MI6 handlers how Soviet officers posing as diplomats tapped him up when he worked for the left-wing magazine Tribune.

Between ten and 14 payments— about £37,000 in today’s money— were made to Foot following meetings in the mag’s offices.

Foot’s status was downgraded from “agent” to “confidential contact” in 1968 after he criticised the the Soviet repression of the Prague Spring in Czechoslovakia.

Foot led the party between 1980 and 1983.