LONDON (Reuters) - The widow of a Russian dissident murdered in London plans to challenge a decision by Prime Minister Boris Johnson’s government not to publish a report on alleged Russian meddling in Britain, a lawyer representing the widow said.

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Marina Litvinenko, whose husband Alexander, a former KGB agent, was murdered with a radioactive isotope in 2006, sent Johnson a letter on Wednesday saying she planned to take legal action, lawyer Elena Tsirlina said.

“A response is now expected by 4 p.m. on 19 November 2019,” Tsirlina said in a statement, adding Litvinenko would only proceed if she secures funding via the CrowdJustice fund-raising site by that date.

Litvinenko’s page on the site said there was “a profound public interest in the information being disclosed to the public, so they are fully informed of the extent of Russian interference in British politics before they go to the polls on 12 December 2019.”

The report by parliament’s Intelligence and Security Committee (ISC) has been cleared by Britain’s security services but it has not yet been approved for publication by Johnson’s office, meaning it will not be released before the election since parliament has shut to allow for campaigning.

Britain has accused Russia of meddling and trying to interfere in elections in the West, which Moscow denies.

The ISC was examining allegations of Russian activity aimed at the United Kingdom, including in the 2016 referendum on EU membership, when Johnson was a leading Leave campaigner.

U.S. intelligence agencies have accused Russia of interfering in the 2016 U.S. presidential election, which was won by Republican Donald Trump.

Hillary Clinton, who ran as the Democratic Party’s candidate in 2016, said earlier this week the failure to publish the report was “inexplicable and shameful.”

According to a British public inquiry in 2016, two Russians carried out Litvinenko’s murder, one of them a former KGB bodyguard who became a Russian lawmaker, in an operation probably ordered by Russian President Vladimir Putin.

Moscow has denied the allegations.