The European Union has accused Hungary of spreading "ludicrous conspiracy theories" after it launched a campaign featuring Jean-Claude Juncker and George Soros which claimed they were plotting to endanger national security.

Hungary’s campaign features the grinning faces of Mr Juncker and the Hungarian-American philanthropist alongside the slogan "You have the right to know what  Brussels is preparing for."

It claims the EU plans to prevent member states from protecting their borders by introducing compulsory refugee quotas and relaxed immigration rules, warning that this would endanger Hungarian citizens.

But on Tuesday afternoon  Margaritis Schinas, the European Commission’s press spokesman, dismissed the campaign as pure fiction.

“The Hungarian government campaign beggars belief,” he said. “It is shocking that such a ludicrous conspiracy theory has reached the mainstream to the extent it has. There is no conspiracy. Hungarians deserve facts not fiction.”  

He added:  “It is not true that the EU undermines border protection. Quite the contrary. And there are zero plans for so-called humanitarian visas. Member states decide to what level they want to accept legal migration.”

Hungary’s nationalist government has repeatedly clashed with Mr Soros, accusing him of enjoying undue influence over EU policy-making due to his considerable influence and wealth, in a campaign that has been accused of anti-Semitic overtones.

But the decision to include Mr Juncker in the same campaign illustrates how Hungary’s hostility towards Brussels has escalated ahead of European elections that are likely to see a surge in support for populist parties.

Despite being in the same European party as Mr Juncker – the centre-right EPP – Hungarian prime minister Viktor Orban has a strained relationship with the European Commission chief. 

In recent years the pair clashed over the EU’s refugee policy, with Hungary refusing to accept quotas on asylum seekers at the height of the crisis.