U.K. Prime Minister Theresa May and France's President Emmanuel Macron hold a joint press conference in the grounds of the Elysée Palace in Paris on June 13, 2017 | Christophe Archambault/AFP via Getty Images Macron: ‘Door still open’ for UK if it changes mind on Brexit Once Brexit has begun, ‘it’s much harder to come back,’ French president says.

PARIS — French President Emmanuel Macron said Tuesday that while the "door is still open" for the U.K. to remain in the EU, it would be "much harder" to reverse the Brexit process once it has started.

Speaking at a joint press conference with British Prime Minister Theresa May in Paris, Macron was asked if he agreed with German Finance Minister Wolfgang Schäuble's comment earlier in the day that the U.K. "would find open doors" if it changed its mind about leaving the bloc.

"For the countries of the European Union, as long as the decision to organize this exit is not completed, it's possible to come back on it," Macron said. "But we have to be clear: once it has begun, it's much harder to come back."

May underscored that Brexit talks would start on schedule — "next week" — while Macron said France wanted talks to start as soon as possible, and be led by the European Commission instead of state by state.

At the start of the conference May struggled with her papers, which were briefly ruffled by wind in the Elysée presidential palace's back garden. Macron joked that the wind would not get the better of them.

Asked a question in English, the president replied in French, saying he wanted to avoid "pointless polemics" if he spoke English while in France.

After a working dinner, Macron and May vowed to cooperate more closely against terrorism, notably via measures to crack down on propaganda on social media.

The two countries would work to pressure social media firms to remove pro-terrorist content more quickly from their sites — in under 48 hours, they said. Macron and May also vowed to improve access to encrypted communications while boosting cooperation between EU states of "digital evidence" against terrorists.

Having taken two questions, the leaders headed off to watch a France-England football match at the Stade de France near Paris. "Unfortunately, one country has to win," Macron joked.