A dossier drawn up by Alexander Litvinenko on the Kremlin's takeover of the world’s richest energy giant will be given to Scotland Yard today as police investigate the former KGB spy's secret dealings with some of Russia's richest men.

It emerged yesterday that Litvinenko travelled to Israel just weeks before he died to hand over evidence to a Russian billionaire of how agents working for President Putin dealt with his enemies running the Yukos oil company.

He passed this information to Leonid Nevzlin, the former second-in-command of Yukos, who fled to Tel Aviv in fear for his life after the Kremlin seized and then sold off the $40 billion company.

Nevzlin told The Times that it was his “duty” to pass on the file. “Alexander had information on crimes committed with the Russian Government’s direct participation,” he said.

“He only recently gave me and my attorneys documents that shed light on the most significant aspects of the Yukos affair.”

Investigators have told The Times that Litvinenko had apparently uncovered “startling” new material about the Yukos affair and what happened to those opposing the forced break-up of the company.

Several figures linked with Yukos are reported to have disappeared or died in mysterious circumstances while its head, Mikhail Khodorkovsky, and others have been jailed.

Originally it was Litvinenko’s vocal opposition to President Putin’s rule that led to accusations of Russia’s secret service involvement in his death, but police are investigating whether he made enemies through his links with a number of oligarchs.

Detectives involved in what they admit is one of the most complicated inquiries Scotland Yard has faced say that they are working through Litvinenko’s formidable list of friends and foes, which includes some of the world’s wealthiest men.

One figure close to the investigation said: “At present we have a bewildering number of theories and names put to us, and we must establish some firm evidence.”

Friends of the former spy have claimed that on his deathbed Litvinenko named a number of men linked to the Kremlin who he claimed were targeting him.

They reportedly include a diplomat based at the Russian Embassy in London until last year who is now back in Moscow. Litvinenko reportedly complained that the man was harassing him after his home was firebombed a fortnight before he was poisoned.

Police are still piecing together how Litvinenko spent the last 72 hours before he fell ill and searching for any further traces of the radioactive isotope, polonium-210, that is thought to have poisoned him.

A post-mortem examination is expected to be carried out today on the former KGB colonel, who acquired British citizenship last month.

Forensic scientists are hoping that polonium-210 found in the Itsu sushi bar in Piccadilly and the Millennium Hotel, both of which Litvinenko visited on November 1, may yield a fingerprint that could help investigators to track down where it came from.

Experts have begun decontaminating the sushi bar, but police were last night still examining guest rooms at the hotel in Grosvenor Square and Litvinenko’s North London home.

His wife, Marina, 44, and 12-year-old son, Anatole, have been examined and neither has been contaminated.

Boris Berezovsky, the exiled oligarch, who employed Litvinenko and who has accused the Kremlin of having a hand in his poisoning, is also reported to have been tested.

More than 300 people have contacted a helpline set up by the Health Protection Agency to be checked for contamination. So far nobody has proved positive.

John Reid, the Home Secretary, said that the Government was doing all it could to warn the public of possible health risks, but added that he had no plans to make a statement to MPs about Litvinenko’s death.

David Davis, the Shadow Home Affairs spokesman, will raise the matter in the Commons today. He said: “It is essential that other dissidents living in Britain are reassured about their safety and there are also questions about how polonium-210 came to be used in Britain.”

Sir Menzies Campbell, the Liberal Democrat leader, said that the Government should have been “much tougher” on Mr Putin and relations would have to be carefully considered if Litvinenko’s death turned out to be the result of “state terrorism”.

Peter Hain, the Northern Ireland Secretary, admitted in a BBC TV interview yesterday that relations with the Kremlin were now “very tricky”. He accused Putin of “huge attacks” on liberty and democracy. He told Sunday AM on BBC One that the President’s record had been “clouded” by events including the “extremely murky murder” of the Russian journalist Anna Politkovskaya.

Foreign and Commonwealth Office officials have asked Yuri Fedotov, the Russian Ambassador, to have the authorities in Moscow make available any information that might assist in the investigation.

Energy Giant

— Yukos was formed by the Russian Government in April 1993 with the merging of hundreds of state-owned oil industry entities

— It became Russia’s first fully-privatized oil company in 1996

— It employs 100,000 people and is involved in every aspect of the oil industry from drilling to the filling station

— In the past five years it has increased its overseas operations, acquiring significant stakes in Slovakian and Lithuanian oil pipeline operators. It is also involved in a proposed Russia-China pipeline