A European Commissioner who was arrested as a dissident by the KGB has offered to explain to Jeremy Hunt the difference between the EU and the Soviet Union.

Vytenis Andriukaitis was one of a flood of European politicians and diplomats who voiced their outrage after the Foreign Secretary compared the European Union with the communist-era USSR.

In his keynote speech to the Conservative Party conference in Birmingham on Sunday, Mr Hunt accused Brussels of seeking to “punish” Britain for wanting to leave the EU and compared it to the Soviet Union trying to stop its citizens leaving.

The comment – which came just days after Theresa May demanded “respect” from the EU – was denounced as “unworthy of a British Foreign Secretary” by the former head of the UK’s diplomatic service, Lord Ricketts.

His successor as the Foreign Office’s Permanent Secretary, Sir Simon Fraser, described it as a “shocking failure of judgment”.

Health Commissioner Mr Andriukaitis wrote on Twitter: “Dear Jeremy Hunt. I was born in (a) Soviet gulag and been imprisoned by KGB a few times in my life.

“Happy to brief you on the main differences between EU and Soviet Union. And also why we escaped the USSR. Anytime. Whatever helps.”

Mr Andriukaitis’s family were among tens of thousands of Lithuanians deported by Stalin to labour camps in Siberia in 1941. The Commissioner himself was born there in 1951 and did not see his Baltic homeland until seven years later.

As an adult, he was part of the dissident underground opposing communist rule, and was arrested and questioned by the KGB secret police.

In Brussels, the European Commission’s chief spokesman Margaritis Schinas also suggested the new Foreign Secretary needed to learn some history.

“I would say, respectfully, that we would all benefit, and in particular foreign affairs ministers, from opening a history book from time to time,” Mr Schinas told a press conference. “That’s the only comment I have.”

German Europe minister Michael Roth said bluntly: “Sorry, Jeremy Hunt, the EU is no prison!”

Meanwhile, Latvia’s ambassador to the UK retorted that the EU had brought her country “prosperity, equality, growth, respect” after decades in which the Soviet Union ruined the lives of its people.

And Estonia’s ambassador in London, Tiina Intelmann, described Mr Hunt’s comments as “insulting” to those who lived under Soviet domination before the collapse of the communist regime in 1991.

In his speech on Sunday, Mr Hunt recalled a visit to Latvia, during which he observed how the Baltic state had developed into “a modern democracy, part of both Nato and the EU” after breaking free of the Soviet Union.

And he asked: “What happened to the confidence and ideals of the European dream? The EU was set up to protect freedom. It was the Soviet Union that stopped people leaving.

“The lesson from history is clear: if you turn the EU club into a prison, the desire to get out won’t diminish, it will grow, and we won’t be the only prisoner that will want to escape.”

Conservative Party annual conference 2018
Foreign Secretary Jeremy Hunt speaks at the Conservative Party annual conference in Birmingham (Stefan Rousseau/PA)

Lord Ricketts, who was the Foreign Office’s most senior civil servant from 2006-10 before serving as National Security Adviser and ambassador to France, responded on Twitter saying: “This rubbish is unworthy of a British Foreign Secretary.

“The EU isn’t a Soviet-style prison. Its legal order has brought peace and prosperity after a century of war.

“Our decision to leave was always going to leave us worse off. The only punishment is the self-inflicted variety.”

And Sir Simon Fraser, who led Britain’s diplomats from 2010-15 and is now vice-chairman of foreign affairs at think-tank Chatham House, said: “I agree with Lord Ricketts, my predecessor as permanent secretary.

“Whatever you think about Brexit, shocking failure of judgment for British Foreign Secretary to compare European Union with Soviet Union.”

Latvian ambassador Baiba Braze said: “Soviets killed, deported, exiled and imprisoned 100 thousands of Latvia’s inhabitants after the illegal occupation in 1940, and ruined lives of 3 generations, while the EU has brought prosperity, equality, growth, respect.”

Ms Intelmann said: “EU and USSR not comparable. Soviet regime was brutal, I lived under it, comparison is insulting.”

And the Czech Republic’s deputy foreign minister, Tomas Petricek, said Mr Hunt’s comparison was “unfortunate”, adding: “The EU is really not the USSR.

“Our country has its experience of the Soviet sphere of influence. With Brussels we decide together on Europe, with Moscow decisions were made about us without us.”

Ms Braze later appeared to play down any rift with Mr Hunt, sending a second tweet thanking him for his “warm words and memories about his visit to Latvia and UK’s contribution to our freedom” in his speech.

Asked about the Foreign Secretary’s comments, Treasury minister Robert Jenrick told the Press Association: “The point that Jeremy Hunt was making was that we want to continue to have very deep and good relations with the EU and we want the EU to treat us with respect.

“We are friends, we are great trading partners and of course we have a very long history together, working on so many different levels – as security allies, as partners and as friends.”