Hillary Clinton has condemned Theresa May for the decision of Conservative MEPs to back the “authoritarian” government of Hungary. 

The former US secretary of state and presidential candidate warned on Tuesday morning that the European Union was risking a “slide towards autocracy”.

“It’s disheartening to watch Conservatives in Brussels vote to shield Viktor Orban from censure – including British Tories,” Clinton said in a speech at Oxford University.

“They’ve come a long way from the party of Churchill and Thatcher.”

Orban, the Hungarian prime minister, has been accused of running an anti-democratic, Islamophobic and anti-Semitic government.

Last month the European Parliament voted overwhelmingly to back a report recommending action against Hungary.

But Tory MEPs voted to oppose the launch of disciplinary action, which could lead to the suspension of Hungary’s EU voting rights.

Orban has attacked “Muslim invaders” and said migrants are a “poison”.

Labour said it revealed the “acceleration of extremist right wing tendencies” within the Conservative Party.

Since the vote, Orban has lent his support to May and claimed other EU leaders want to “punish” the UK for the Brexit vote.

Speaking at the Bonavero Institute of Human Rights today, Clinton said the “EU and the people of Europe will resist the backsliding we are seeing in the east”.

“Let’s not be fooled by the masquerade that countries like Hungary and Turkey are still real democracies, just illiberal ones. Illiberal democracy is a contradiction in terms,” she said.

“To be a democracy takes more than an election, even a free and fair one.

“It also requires free expression and a free press, the rule of law and an independent judiciary. Vibrant civil society and transparent and responsive institutions that are accountable to all citizens and protect their rights equality.

“Without these things illiberal democracy is no democracy at all – it’s just authoritarian by another name.”

Clinton warned: “The slide towards autocracy is at least as grave threat to the European project as the financial crisis or Brexit.”

Environment Secretary Michael Gove has defended the action of Tory MEPs on the grounds that it is wrong for the European Parliament to interfere in the “internal democracy” of a member state.