MOSCOW, July 7 (RIA Novosti) - The Russian Federal Security Service (FSB) has completed an inquiry into an ex-security officer's claim on spying for the British intelligence and launched a criminal case on espionage charges, the FSB press service said Saturday.

Last week FSB said the alleged spy Vyacheslav Zharko had disclosed the names of four British intelligence officers, and given locations in Europe where meetings had taken place, including information regarding the assignments he had been given.

"We have inquired into the matter and received enough information, which indicates that between 2003 and 2007 British SIS officers recruited him and later used as an agent for spying to the detriment of Russian Federation's security," the FSB said in a statement.

Zharko turned to the FSB following May 31 news conference given by another former security officer Andrei Lugovoi, who accused Russia's fugitive tycoon Boris Berezovsky of working for British intelligence.

Berezovsky, now living in Britain, has denied contact with British intelligence. "The British intelligence services know only too well that I am not listed on any organization, including MI6," Berezovsky said in response to Lugovoi's accusations.

Lugovoi was accused by the Crown Prosecution Service on May 22 of murdering former Russian security officer Alexander Litvinenko, who had fled to the U.K. in 2000, claiming his life was in danger after refusing an order to assassinate his patron Berezovsky.

Though Litvinenko is thought to have been poisoned with radioactive Polonium-210, no official autopsy report has so far been made available. Lugovoi has vehemently denied the accusations against him claiming they are politically motivated.