Paris: French President Emmanuel Macron said on Tuesday that the door to the European Union remains open to the United Kingdom as long as exit negotiations are not concluded, but it would be difficult to walk back once negotiations start.

Asked at a joint news conference with British Prime Minister Theresa May in Paris whether he agreed with German Finance Minister Wolfgang Schaeuble who earlier told Bloomberg that Britain would find "open doors" if it changed its mind, Macron replied: "The door of course is still open as long as Brexit negotiations have not been concluded, but a sovereign decision to leave the EU has been taken and I respect that decision."

May said the timetable for Brexit negotiations remained on course with talks due to start next week. The two leaders met for a working dinner before together attending a France vs England friendly soccer match at the Stade de France stadium in Paris.

Macron's comments that it was not too late for Britain to remain inside the EU came as May faces a tug-of-war within her own party over her Brexit strategy following a disastrous snap election which she called.

Before the election May had proposed a clean break from the EU, involving a withdrawal fromEurope's single market, but now weakened with a minority government, some in her party are calling for a more business-friendly approach.

After meeting May for the first time during the French presidential campaign last February,Macron had said the British prime minister should not expect any favours from the European Union during Brexit talks.

He told reporters outside 10 Downing Street at the time that "an exit is an exit."

On Tuesday, May and Macron also said they had agreed on an action plan on counter-terrorism. Both countries have been hit by deadly Islamist militant attacks in recent months.

Macron said Internet companies would be asked to do more to remove content promoting terrorism, access to encrypted content on online messaging systems would be widened, and co-operation with the United States on online content would be improved.