Before they join the EU, people are "ready to do everything they are asked", but when they are in the EU, they are "bored and not interested", he said.

Now the British vote to leave the EU requires that EU leaders and people "understand what is going on", he said. "We have to think what we did wrong and what we should do better."

Kiska said that he was "not happy" with Brexit and that Europe needed "empathy" towards the British. He criticised calls for the quick invocation of article 50, which organises a country's exit from the EU, and calls by some countries for businesses to move their offices from the UK.

"We have to calm down, and not push the British people and politicians to do things very fast," he said.

Kiska, whose powers in Slovakia are mainly honorary, was in Brussels as his country starts it six-month presidency of the EU Council.

A businessman turned philanthropist, he was newcomer in politics when he defeated current prime minister Robert Fico in 2014's presidential election.

Duty to help refugees

He said that on migration, the most delicate topic for the Slovak EU presidency, he had "a different approach" to Fico.

"It's our duty to help people fleeing war and terrorism," he said. Asked if that applied to Muslims, he said "Yes".

The Slovak government has been a staunch opponent of the EU scheme to share asylum seekers and Fico in May said that "Muslims have no place in Slovakia".

Kiska admitted that Slovakia’s position on migration was "difficult to understand". He explained that under communism, no migrants came to the country. "It was rather people leaving," he pointed out.

"Now we are free but we still have no migrants," he said, adding that populism was a reason for the Slovaks' limited tolerance to migrants.

"People feel threatened because migration is new and lots of politicians have used this feeling to get votes … Politicians did not explain that there was something new and people should not be afraid."

Putin's blackmail

As energy union is a priority of the Slovak EU presidency, Kiska said that the Nord Stream 2 project for a gas pipeline between Russia and Germany made him "unhappy".

"I'm a big advocate of fighting Nord Stream 2," he said.

He said the project was not needed because the first Nord Stream pipeline and the one that goes from Russia to the EU through Ukraine and Slovakia "have enough capacity".

Nord Stream 2, he said, "is not just business, it's a very strong political decision", he said, adding that it was “the best tool for Putin to blackmail Ukraine”.

Kiska regretted that "one big party stands behind Nord Stream 2", in a veiled reference to the German Social-Democratic Party, which is often considered as sympathetic to Russia.