The British government sought on Tuesday to limit the information it is ready disclose at a planned inquest into the death of Alexander V. Litvinenko, a former officer in the K.G.B. who died of radiation poisoning in London more than six years ago, and the coroner hearing the case said it may now be postponed.
“Due to the complexity of the investigation which necessarily precedes the hearings” Sir Robert Owen, the coroner said, the planned May 1 start date for the hearings could represent “a timetable to which it may not be possible to adhere.”
The inquest would be the first — and likely the only — public forum at which witnesses would testify under oath about the killing, which strained Britain’s relationship with the Kremlin and kindled memories of the cold war.
The prospect of a postponement brought charges from Ben Emmerson, a lawyer representing Mr. Litvinenko’s widow, Marina Litvinenko, that the British government was trying to gag the inquiry in order to protect lucrative trade deals with Russia.
Referring to Prime Minister David Cameron, Mr. Emmerson said on Tuesday that “the British government, like the Russian government, is conspiring to get this inquest closed down in exchange for substantial trade interests which we know Mr. Cameron is pursuing."
He added: "One has to ask what is going on at the highest level of Her Majesty’s Government, particularly when the highest levels are building bridges with the Kremlin."
The British government, he said, had “no right to say to an independent judiciary, ’you may not investigate these issues’. That happens in Russia, for sure.”
“This has all the hallmarks of a situation which is shaping up to be a stain on British justice,” the lawyer said.
Sir Robert, the coroner, said he would rule on Wednesday on the government’s application for a so-called Public Interest Immunity Certificate, usually issued on the grounds of national security, which would prevent the inquest from hearing information on topics without explaining what those issues were.
British analysts say they believe Britain is keen to avoid disclosing any information that might link Mr. Litvinenko to the British security services.
Last December, Mr. Emmerson, the lawyer, told a preparatory hearing that that Mr. Litvinenko was a “registered and paid agent and employee of MI6,” as the British Secret Intelligence Service is known. Mr. Litvinenko also worked for the Spanish intelligence service, Mr. Emmerson said, and both the British and Spanish spy agencies made payments into a joint account with his wife. The lawyer added that the inquest should consider whether MI6 failed in its duty to protect the onetime KGB officer against a “real and immediate risk to life.”
Mr. Litvinenko, who fled Russia in 2000 and styled himself a whistle-blower and foe of the Kremlin, died in November 2006, aged 43, weeks after he secured British citizenship. He had ingested polonium 210 — a rare radioactive isotope — at the Pine Bar of the Millennium Hotel in London’ central Grosvenor Square.
Britain’s Crown Prosecution Service is seeking the extradition from Russia of Andrei K. Lugovoi, another former K.G.B. officer, to face trial on murder charges. Mr. Lugovoi denies the accusation and Russia says its Constitution forbids it from sending its citizens to other countries to face trial.
The coroner has said in previous hearings that he will examine what was known about threats to Mr. Litvinenko and would also seek to determine whether the Russian state bore responsibility. In a deathbed statement, Mr. Litvinenko directly blamed President Vladimir V. Putin, who dismissed the accusation. Mr. Emmerson, the lawyer, complained on Tuesday that the preparations for the inquest were becoming “bogged down” by “the government’s attempt to keep a lid on the truth.”
“It is the government’s secret files that are delaying this inquest.”
British media outlets including the BBC and The Guardian newspaper are opposing the government’s effort to restrict evidence. The Guardian said that “the public and media are faced with a situation where a public inquest into a death may have large amounts of highly relevant evidence excluded from consideration by the inquest. Such a prospect is deeply troubling.”
But the Foreign Office said the authorities had made their application in line with their “duty to protect national security” and the coroner would rule according to “the overall public interest.”