LONDON (Reuters) - Britain cannot have it all as it exits the European Union and cannot leave behind the bloc's problems while benefiting from its advantages, French agriculture minister Stephane Le Foll said on Wednesday.

"You cannot say when exiting the EU you will keep all the advantages but leave behind anything that doesn't suit you," Le Foll said at a briefing in London before a bilateral meeting with his British counterpart Andrea Leadsom.

"It's a choice which results in losing certain advantages which could be taken for granted," said Le Foll, who is also the spokesman for France's Socialist government.

The EU's Common Agricultural Policy (CAP) regulates farm policy across the bloc, providing subsidies to farmers in member states - including Britain - that contribute to its budget.

Britain's vote to leave the European Union spells uncertainty not only for British farmers as subsidies dry up, but also for the CAP's budget because of the looming end to Britain's contributions. Britain's National Farming Union supported Britain remaining in the EU.

Le Foll, who was a vocal opponent of Brexit prior to the referendum, emphasised the importance of continued cooperation with Britain on agricultural issues as well as security, alluding to the problem of migrants who flocked to Calais in the hope of crossing the Channel to Britain.

"We have agricultural and agroindustrial relations around which we must, of course, continue to share and discuss," he said.

"The question of Calais must compel us to continue relations that are productive enough to be able to solve the problems concerning both France and Great Britain," he added.

Le Foll said he would not speak to Leadsom about the CAP, which is to be debated ahead of new guidelines in 2020.

He said Britain's exit should precede the new agricultural policy, citing French President Francois Hollande's demand that the formal exit occur before the EU elections in 2019.

The French minister hosted 19 other European agriculture ministers in France's Loire valley in September to discuss the future of the CAP after Brexit, pointedly not inviting Britain.

Prime Minister Theresa May, at her first European Council meeting in Brussels, said Britain would continue to play a full role in the EU until it leaves, and would be a strong and dependable partner after it left.

(Reporting by Helen Reid; Editing by Tom Heneghan)