PARIS, July 21 (Xinhua) -- French President Francois Hollande on Thursday called on Britain to prepare for talks to leave the European Union(EU) as soon as possible.

Attending a joint news conference with British Prime Minister Theresa May in Paris, Hollande said France respected Britain's decision to leave the EU, but the sooner to open a negotiation on Brexit the better.

"There cannot be discussions, pre-negotiations before the negotiation but there can be preparation for this negotiation. We do understand that your government, which has just been formed, needs time. (But), the sooner the better for the common interest," Hollande told May.

Warning of the "uncertainty" as a result of Brexit, Hollande stressed that Britain should respect free movement of EU citizens if it wants to remain part of the free-trade union.

May said she wanted "to ensure that the negotiations for Britain leaving the European Union are done in a calm and orderly and constructive manner."

"I hope that we can all make the most of the next six months to prepare for these discussions in a constructive way so we maximize the opportunities for both the UK and the EU," she added.

May also expressed determination "to maintain the closest possible economic relationship" between London and Paris after Britain's referendum on its EU membership.