Lubov Chernukhin has donated about £2m to the Tories since 2012.

Electoral Commission figures show she personally donated another £80,250 in late 2021.

The Conservative Party said she is a British citizen with a "democratic right to donate to a political party".

Mrs Chernukhin's lawyers told the BBC she does not have any comment to make regarding her donations, which are a matter of public record.

They have previously said her "donations to the Conservative Party have never been tainted by Kremlin or any other influence".

In recent public comments reported in the media, Mrs Chernukhin condemned "all Russian military aggression in Ukraine" and called for the "strongest possible sanctions against Putin's regime and its enablers".

"I remain hopeful that the UK and its global allies will continue to stand up to the Kremlin and to protect Ukraine and its people, now engulfed in the horrors of war," Mrs Chernukhin was quoted as saying.

Mrs Chernukhin and her husband, Vladimir Chernukhin, are both British citizens and are entitled to donate to UK political parties and vote in elections.

Mr Chernukhin, 53, a former deputy minister of finance under President Vladimir Putin left Russia for London in 2004 after being sacked by the president.

Since Mr Putin ordered an invasion of Ukraine last week, the Conservative Party has been criticised for accepting donations from people with links to Russia.

Labour MP Bill Esterson drew attention to Mrs Chernukhin's donations to the Conservative Party during Prime Minister's Questions on Wednesday.

Figures released by the Electoral Commission on Wednesday show Mrs Chernukhin made two donations last year - £13,750 in October and £66,500 in December.

Mr Esterson asked Mr Johnson if he would instruct the Conservative Party to hand her donations to Ukrainian humanitarian causes.

Mr Esterson said: "I know he doesn't want to tar everyone with Russian links with the same brush and neither do I, but leaked documents show that Vladimir Chernukhin received eight million US dollars from a Russian member of parliament, an ally of Putin who was later sanctioned by the United States.

"This is an opportunity for the Conservative Party and for the prime minister to end the suspicion of conflict of interests with Putin whilst showing solidarity with the Ukrainian people."

In reply, Mr Johnson said: "It is absolutely vital that if we are to have a successful outcome in what we are trying to do collectively, united with Ukraine, that we demonstrate that this is not about the Russian people, it is about the Putin regime."

In a later statement, Labour's deputy leader Angela Rayner said "dangerous links to Putin's cronies must be rooted out".

"If this government is serious about taking the toughest measures to eradicate Putin's influence in Britain, they must first get their own house in order," she said.