In an interview with the BBC’s Nick Robinson, Mr Farage was challenged over his judgement and past statements, including when he named Russian President Vladimir Putin as the world leader he most admired in 2014.

“I said I disliked him as a person, but admired him as a political operator because he’s managed to take control of running Russia,” Mr Farage said.

He was then pressed over a social media post in February 2022, when he claimed the Russian invasion of Ukraine was “a consequence of EU and Nato expansion”.

Mr Farage said he had been arguing since the 1990s that “the ever eastward expansion” of the Nato military alliance and the EU was giving President Putin “a reason to [give to] his Russian people to say they’re coming for us again and to go to war”.

He added: “We provoked this war. Of course, it’s [President Putin’s] fault.”

Russia launched a full-scale invasion of Ukraine in February 2022. It followed the occupation of the Crimea and Donbas regions in 2014.

Ukraine is not a member of the EU or Nato, which is made up of 32 countries across Europe and North America.

However, the country applied to join both blocs following the Russian invasion.

Nato was formed in 1949 by 12 countries, including the US, UK, Canada and France.

After the Soviet Union’s collapse in 1991, many Eastern European countries joined including Hungary, Poland and Estonia.

The EU has also expanded since the 1990s, with a number of eastern European countries joining in 2004.

In the interview, Mr Farage also accused the Conservatives of failing to deliver on Brexit.

As the leader of UKIP, he was a key figure in the campaign to leave the EU.

While the issue dominated the 2019 general election, with Boris Johnson campaigning on the slogan “Get Brexit Done”, it has not featured prominently in the current campaign.

Asked if he stood by his previous claim that Brexit had failed, Mr Farage said: “No, it’s not a failure but we failed to deliver.

“It can’t be a failure. We’ve left the European Union. We’re now self-governing.”

But he added: “Brexit has failed those who voted for it, believing that immigration numbers would be reduced.”

Net migration – the difference between the number of people coming to live in the UK and those leaving – has risen sharply since 2021, when the UK left the EU.

This has been driven by non-EU nationals coming to the UK.

Net migration reached record levels in 2022 before reducing slightly the following year.

Reform UK has said it backs a freeze on non-essential immigration to relieve pressure on housing and public services, increase wages and “protect our culture identity and values”.

Mr Farage also faced questions over his stance on climate change and whether he believed it is not really a “crisis”.

“I do think ever since the late 1980s that perhaps there’s been a bit of hype around this, and I think that perhaps is wrong,” he said.

“All we ever talk about is fear rather than solutions.”

He added: “We spend too much time hyperventilating about the problem rather than thinking practically and logically what we can do.”

Mr Farage branded the Labour and Tory net zero policies as “nonsense”, claiming £30bn a year could be saved by dropping their climate pledges.