Mr Fico pointed to the recent examples in the UK and Italy, which saw the countries turn away from the EU.
Britain voted to leave the superstate – Brexit – while the Mediterranean nation’s future is uncertain after the Prime Minister Matteo Renzi resigned following Italians overwhelmingly rejecting his package of reforms.
The constitutional reforms Italians shunned has led the populist 5Star movement to call for a referendum on the country’s continued membership in the eurozone.
And across the continent Eurosceptic parties are gaining support, including in the Netherlands and France, which also pose a real threat to the stability of the EU.
As Slovakia handed the six-month rotating presidency of the Council of the EU to Malta on January 1, Mr Fico added: “I am asking EU leaders to stop with adventures like the British and Italian referendums . . . on domestic issues which pose a threat to the EU.”
And concerns over the European project were deepened with the numbers of migrants entering the continent, which reached more than one million in 2015, and was dubbed the migrant crisis.