The wife of one of Vladimir Putin’s former cronies has given the Conservative Party £30,000 to dine with Defence Secretary Gavin Williamson.

The donation by Lubov Chernukhin, who is married to a former Russian deputy finance minister, comes a fortnight after Mr Williamson said a Russian cyber attack on Britain’s electricity supply could kill thousands.

Mr Williamson will give Mrs Chernukhin a tour of Churchill’s War Rooms in Whitehall and host a dinner for her and a group of her friends there after she made two successful bids at last week’s Conservative Black and White Ball.

The donation is by Lubov Chernukhin, who is married to a former Russian deputy finance minister (pictured with Vladimir Putin)

Banker Mrs Chernukhin, who once successfully bid £160,000 at a Tory fundraiser to play tennis with Boris Johnson, also paid £20,000 to dine with Scottish Conservative leader Ruth Davidson in Edinburgh.

The Tories deny that Mrs Chernukhin, now a British citizen, is a Putin crony. Her billionaire husband, Vladimir, 49, fell out of favour with the Russian president when he was forced out of his post running a state-run Moscow bank.

Gavin Williamson (pictured) will give Mrs Chernukhin a tour of Churchill’s War Rooms in Whitehall

Mrs Chernukhin has contributed £554,000 to Conservative coffers since 2012, when she was declared an ‘impermissible donor’ after attempting to give the party £10,000. She has now given the Tories £211,000 in the past six months.

Mr Williamson said last month that Moscow had been photographing UK power stations in a threat to damage our infrastructure.

The Mail on Sunday has also established that the wife of the grandson of the authoritarian Kazakh ruler was among donors at the Black and White Ball.

Aida Aliyev, wife of Nurali Aliyev, grandson of Kazakh president Nursultan Nazarbayev, bid £5,000 for Royal Opera House tickets. Mr Nazarbayev has been accused of human rights abuses and ballot-rigging.

The Black and White Ball donations appear to reflect a U-turn by Mrs May. Last year, she reportedly wanted to bar oligarchs from Tory fundraising events because she disapproved of the way David Cameron allowed Russians with opaque pasts to rub shoulders with Ministers.

The Conservative Party declined to comment.