British EU referendum 'very risky' France warns as Cameron visits Paris

David Cameron started a tour of European capitals on Thursday to prepare for the UK's EU referendum AFP

French Foreign Affairs Minister Laurent Fabius warned that the UK's planned referendum on staying in the European Union (EU) was "very risky" on Thursday ahead of a visit by UK Prime Minister David Cameron to Paris and other European capitals.

Cameron on Thursday started a tour that takes him to The Hague, Paris, Warsaw and Berlin to discuss changing EU treaties, notably on migration, ahead of the referendum, which he has promised to hold before 2017.

Fabius, who was to attend Cameron's dinner with President François Hollande on Thursday evening, was less than enthusiastic about the vote, which the British PM has said could take place next year.

"He launched this referendum project, it is something very risky," he told France Inter. "We hope Britain stays in the European Union, nevertheless there are things that need to be improved."

France is not opposed to reforming the EU, he insisted, but warned that "Brexit", as Britain leaving the bloc has been called, could lead to its "dismembering".

"The British population has become used to being told: 'Europe is a bad thing', and the day they are asked to decide, the risk is that they say Europe is a bad thing," he said.

Britain would "certainly" have the most to lose if it left the EU, but the bloc would also suffer, Fabio's said.

Britain "is a military power, a diplomatic power. If such an important country leaves Europe it will give an extremely negative impression of Europe."