Israeli researchers say a Soviet-era record indicates the President of the Palestinian Authority, Mahmoud Abbas, worked in the early 1980s for the KGB.
Mr Abbas was recorded as an “agent of the KGB” in a report smuggled to the UK by defector Vasily Mitrokhin, in accordance with Gideon Remez and Isabella Ginor.
The president’s spokesman described the claim as a foolish Israeli “smear”.
It comes as Russia attempts to organise a meeting between Mr Abbas and Israeli Prime Minister Benjamin Netanyahu.
The Palestinian leader said earlier this week that Israeli officials had asked to delay until an unspecified later date, although he had consented to see Mr Netanyahu in Moscow on Friday.
The two men shook hands this past year at a global climate change summit in Paris, but have not attended public talks that were substantial since 2010.
Mr Remez and Ms Ginor told Israel’s Channel 1 television that Mr Abbas was named in a record they’d found in the Mitrokhin Archive, stored at the University of Cambridge.
“‘Krotov’ – Abbas, Mahmoud, born 1935, origin Palestine, member of the executive committee of Fatah, PLO, Damascus, agent of the KGB,” says the simple entry.
Mr Abbas was born in 1935. After the creation of the State of Israel in 1948 his family fled to the Syrian capital, where he was trained.
The Thomas Fessy in Jerusalem of the BBC notes the record will not say Mr Abbas would have been recruited, whether he was paid, and how long he might have worked for the KGB although the biographical details are correct.
An advisor to the president told the BBC Israel made up the allegation.
He said Mr Netanyahu remained unwilling to meet Mr Abbas in a possible new round of peace talks organised by Russian President Vladimir Putin, himself a former KGB staff member.
Palestinian officials said the PLO was working with Moscow in the early 1980s. Mr Abbas, they added, failed to have to be a Soviet representative to liaise with this.