The anti-bailout government of Greece’s new leftist prime minister, Alexis Tsipras, has been announced, with the post of economics minister – chief negotiator with the country’s international creditors – going to a radical economist who has described austerity programmes as “fiscal waterboarding”.

With Greece set on a collision course with Europe over the Syriza-led government’s plans to reverse draconian belt-tightening and renegotiate the country’s massive debts, Yanis Varoufakis, who calls himself an “accidental economist”, confirmed in a radio interview on Tuesday morning that he would take up the key position.

The rest of the government, the first in Europe to openly oppose the bailout conditions demanded by the European Union and International Monetary Fund, was announced by the newly installed minister of state, Nikos Pappas, on Tuesday afternoon.

There are 39 cabinet members in total, of whom six are women,with academics taking up a number of key cabinet posts.

Tsipras chose economist and veteran leftwing politician Giannis Dragasakis as deputy prime minister, responsible for overseeing negotiations with the “troika” of the European Commission, the IMF and the ECB.

Panos Kammenos, party leader of coalition partner the Independent Greeks, has been made defence minister, while the blind MP Panaghiotis Kouroumblis will helm the health ministry.

The cabinet was being sworn in on Tuesday afternoon.

One of Varoufakis’s top priorities will be to deliver on Tsipras’s election pledge to renegotiate the terms of Greece’s €240bn bailout deal, despite widespread and sometimes forceful opposition from other European countries, led by Germany.

Varoufakis, 53, studied in Britain and has also taught in Australia, Greece and the US. In pre-election interviews he promised to end what he described as Greece’s humanitarian crisis, slice a chunk off its €320bn debt mountain, and destroy the country’s oligarchs who “viciously suck the energy and the economic power from everybody else”.

A prolific blogger and media commentator who dresses in brightly coloured shirts and jeans, Varoufakis – who has dual Greek and Australian nationality – abandoned a job at the University of Texas to join Tsipras’s team in the election runup, and celebrated Sunday’s result by paraphrasing Welsh poet Dylan Thomas, saying: “Greek democracy today chose to stop going gently into the night. Greek democracy resolved to rage against the dying of the light.”

Syriza failed by just two seats to win an outright majority in Greece’s 300-seat parliament and on Monday formed a coalition government with the small rightwing Independent Greeks (Anel) party.

Analysts have described it as an unnatural alliance and warned it might not survive long, pointing out that ANEL - best-known for vitriolic attacks on Germany and the Troika and for the occasional unashamedly antisemitic, racist and homophobic outbursts of its populist leader, Panos Kammenos – are unpredictable and that the two parties, while they agree on the need to end austerity, hold directly opposing views on many key social issues including immigration.

While the IMF said it was ready to continue supporting Greece and looked forward to discussions with the new government, the head of the European commission, Jean-Claude Juncker, warned that a reduction in the country’s debt was “not on the radar”. The EU issued a stiff statement that Greece would risk its place in the eurozone if it fails to meet its austerity and debt commitments.

Syriza has promised to reverse many of the huge public-sector spending cuts and wage and pension reductions implemented by the previous centre-right government, but several eurozone countries made clear they thought its plans were unrealistic.

“In our view it is important for the new government to take action to foster Greece’s continued economic recovery,” Steffen Seibert, a spokesman for the German chancellor, Angela Merkel’, said. “That also means Greece sticking to its previous commitments.”

The British prime minister, David Cameron, was more conciliatory on Monday night, congratulating Tsipras and welcoming his “intention to tackle corruption and increase tax transparency across Greece”.

But the UK chancellor, George Osborne, said Syriza’s promises to voters appeared “very difficult to deliver” and “incompatible with what the eurozone currently demands”, warning that any resulting uncertainty would have an impact on Britain.

Varoufakis has long criticised Europe’s handling of the economic crisis, attacking the conservative economic orthodoxy that demands budget rigour and market-friendly structural reforms.

That approach amounted to “a cynical transfer of banking losses on to the shoulders of the weakest taxpayers”, he said on his blog earlier this month. He has also likened the tough terms of bailout deals to “fiscal waterboarding” that risked converting southern Europe into “a form of Victorian workhouse”.