"It is essential to bear one clear principle in mind: the single market is not divisible; access to the single market is inseparable from respecting its rules," Villeroy said in Germany.

"This makes a simple free trade agreement such as that proposed by (UK Prime Minister) Theresa May very difficult and there can be no cherry picking with regard to Europe."

Britain is expected to start formal divorce proceedings in March and negotiations are expected to take at least two years.

May earlier this month said that Britain will quit the single market in a move dubbed 'hard Brexit' but would seek the greatest possible access to European markets.

(Reporting by Joern Poltz; Writing by Balazs Koranyi)