Nationalist leader Volen Siderov on Friday urged Bulgarian authorities to consider a referendum on the country's EU membership.

In a statement from Parliament's rostrum, Siderov argued that his Ataka party's theses on the downsides of the EU had been accepted by countries "as far [from Bulgaria] as Britain".

"Eight or nine years after [Bulgaria's accession] the Bulgarian is just as poor," Siderov told lawmakers, pointing out that Brussels had forced Sofia into closing nuclear reactors and cutting trade with "much of the world".

"An all of that was called prosperity," the leader noted.

He also referred to Britain as a US fifth column. "Could it be that the UK's exit from the EU means something bad is being prepared in Europe?," he asked rhetorically, in an apparent reference to NATO's decision to bolster its eastern flank in view of potential aggression coming from Russia.

A vast majority of Bulgarians back the country's EU membership, which began in 2007. On Friday, after results were announced of the Brexit referendum, Prime Minister Borisov joked one day Bulgaria, Romania and Greece might end up being the only EU member states, in an apparent reference to broad support for the union among their citizens.

Siderov's Ataka party has long advocated closer ties between Bulgaria and Russia, urging the former to quit both NATO and the EU.