[This article is subject to a legal complaint]

ALLEGATIONS that a British security company with wealthy Russian clients paid a police officer in the extradition unit for sensitive information are being investigated by Scotland Yard.

The officer, who has been moved temporarily from his post, is alleged to have provided Home Office and police intelligence concerning moves by Moscow to extradite a number of Russia’s wealthiest and most wanted men living in Britain.

Anti-corruption detectives are examining documents detailing the client accounts of ISC Global (UK), a London-based security firm at the centre of the investigation. The financial dossier, seen by The Times, shows that ISC was paid more than £6 million from offshore companies linked to the most vocal opponents of President Putin of Russia.

Between 2001 and 2005, ISC provided a variety of specialist security services, including “monitoring” the Kremlin’s attempts to extradite key clients to Moscow, where they face fraud and tax evasion charges.

A former ISC insider passed the dossier to the intelligence arm of the anti-corruption squad in February. The informant directed handlers to a series of ISC payments, totalling £20,000, made to a recipient codenamed Noah. Detectives from the Scotland Yard professional standards directorate were told that Noah could be a reference to an officer in the extradition unit who was friendly with one of ISC’s bosses.

The officer under investigation has been identified as Detective Sergeant Gary Flood. His home and office were raided last month.

A spokesman for the Metropolitan Police said yesterday: “We are conducting an investigation into allegations that a serving officer made unauthorised disclosures of information to another individual in exchange for money.”

Anti-corruption detectives are examining the relationship between Sergeant Flood and a former Scotland Yard detective, one of the original partners in ISC. The men admit to being close friends for more than 25 years but deny any impropriety and are willing to co-operate with the inquiry.

Sergeant Flood has not been suspended. His lawyer said: “All allegations of impropriety in whatsoever form are categorically and unequivocally denied.”

ISC Global was set up in October 2000 by Stephen Curtis, a lawyer. He was already acting for a group of billionaire Russians led by Mikhail Khodorkovsky and Leonid Nevzlin, who controlled Yukos, Russia’s privatised energy giant.

From his Park Lane offices, Curtis moved their money overseas through complex offshore structures registered in places such as Gibraltar and the British Virgin Islands.

According to well-placed sources, the Yukos oligarchs provided £3million “seed money” to set up ISC a few years before Mr Putin moved to take the oil and gas company back into the Kremlin’s hands. In 2002, the President mounted a popular clampdown on those businessmen, who threatened him politically after they obtained fortunes from the privatisation of former state-owned energy companies given away at knockdown prices by his predecessor, Boris Yeltsin.

A wave of Yukos executives fled to “Londongrad”, as it became known among the estate agents who found them luxury homes. ISC provided them with security services and monitored the extradition process, the documents show.

Between December 2001 and July 2004, Prinstown Investments, an offshore company controlled by the Yukos oligarchs, paid £3.7 million to ISC for these services. A further £1.7 million was paid through other accounts.

The dossier also reveals that Boris Berezovsky, an academic turned tycoon and politician who became Mr Yeltsin’s key adviser, was a client of ISC.

Curtis acted for Mr Berezovsky as well as the Yukos oligarchs. Two companies linked to Mr Berezovsky — Bowyer Consultants Ltd, of Gibraltar, and Tower Management Ltd, in London — appear to have made payments totalling almost £600,000 to ISC.

Mr Berezovsky’s spokesman said that his client was not aware of the Scotland Yard corruption inquiry. He admitted using ISC to protect his family but denied any knowledge or involvement in the alleged procurement of sensitive information.

Mr Berezovsky fled to London five years ago and is wanted in Moscow to face charges of fraud and embezzlement. However, the Home Office granted him political asylum in September 2003.

ISC stopped trading last year after Curtis, the chairman, died in a helicopter crash. Subsequently, two former Scotland Yard officers, Keith Hunter and Nigel Brown, whom Curtis recruited to set up ISC, fell out and Mr Hunter bought the company and renamed it RISC.

A spokesman for Mr Hunter said: “Neither my client nor his associated companies have ever made illegal payments to a Scotland Yard officer.”

Mr Brown, who lives in Israel, said: “Scotland Yard recently contacted me as a result of receiving certain information. I have been asked not to discuss this matter.”

Times Recommends

• Everyone will get vaccine against swine flu
• Artificial sperm and the race to build a baby
• BBC jets out stars to tout for prizes