The former Greek finance minister Yanis Varoufakis is giving advice to the Labour party, Jeremy Corbyn has revealed.

In an interview with his local newspaper, the Islington Tribune, the Labour leader disclosed that Varoufakis was helping “in some capacity”.

“Varoufakis is interesting, because he has obviously been through all the negotiations [with the ECB, European commission and IMF],” he said. “I think the way Greece has been treated is terrible and we should reach out to them.

“I realise we’re not in the eurozone but it’s a question of understanding how we challenge the notion that you can cut your way to prosperity when in reality you have to grow your way to prosperity.”

Senior Labour sources said Varoufakis had no formal advisory role for the party and did not sit on its economics advisory board. But he will give one of the shadow chancellor’s New Economics lectures at the end of March, in which he will deliver advice about finance.

Varoufakis revealed last year that he was “in conversation with the Labour party – the Corbynistas”. He told the BBC’s Daily Politics at the time: “My advice is to shift away from the narrative of austerity – pro-austerity/anti-austerity. Austerity is not the issue.”

He added: “Corbyn has to revive the Harold Wilson strategy of the 60s of reinventing Labour’s values in the context of a technologically driven investment programme.”

Varoufakis resigned as Greece’s finance minister in July 2015 after saying that the leftwing prime minister Alexis Tsipras thought it would be better if he stood down. During the Greek debt crisis he had infuriated eurozone leaders , who applied pressure for him to resign, and at one point he compared Greece’s creditors to terrorists.

The Conservatives were quick to ridicule the links between Corbyn and Varoufakis. Greg Hands, the chief secretary to the Treasury, said it “tells you all you need to know about Labour’s economic strategy”.

He said: “Jeremy Corbyn says he can learn from Varoufakis’s ‘experience in Europe’ but that experience was one of deep recession, capital flight, banks being forced to close for days on end and a government that struggled to pay public sector workers their wages and pensions.” .

Corbyn met Tsipras last month to discuss EU reform. He told the Tribune: “We both want to see an economic strategy around anti-austerity, and we’re both very concerned about the activities and power of the European Central Bank, although Britain is not in the eurozone and isn’t likely to be.”