Ben Emerson, who represents the widow of ex-agent Alexander Litvinenko, said he was troubled by a request from Foreign Secretary William Hague that the London coroner reconsider a decision to release documents from the investigation into Litvinenko's death by poisoning in 2006.
Emerson told the Financial Times Hague was "approaching his coverup responsibilities with alacrity and enthusiasm." He said the latest twist in the Litvinenko case came as Prime Minister David Cameron's administration was making a high-level push to enhance commercial relations with Russia and its president, former KGB man Vladimir Putin.
Emerson called on the government to "scotch once and for all any possible suggestion that David Cameron is so interested in promoting trade with Russia that he's trying to close down this inquest."
Litvinenko died after ingesting a lethal radioactive chemical, apparently while drinking tea in London with two other Russians. Litvinenko became a vocal critic of Putin after he received political asylum in Britain.
Hague said in his request to the coroner that it was not in the public interest to place certain government documents in the public domain, the Times said.