EU opens next Brexit phase, warns of tough talks

European Union leaders agreed Friday to open crucial talks on a future relationship with Britain but warned they would be even tougher than the first tortuous phase of negotiations.

EU President Donald Tusk congratulated British Prime Minister Theresa May after her 27 counterparts endorsed an interim deal on the terms of Britain's divorce, and approved the next stage of discussions.

But although talks will begin in January on a post-Brexit transition period of around two years, they stressed that actual negotiations on future trade ties would not start until March, as they need more clarity on what Britain wants.

"EU leaders agree to move on to the second phase of Brexit talks. Congratulations PM @theresa_may," EU President Donald Tusk tweeted.

May replied on Twitter, thanking Tusk and European Commission President Jean-Claude Juncker and hailing it as a major advance in the negotiations.

"Today is an important step on the road to delivering a smooth and orderly Brexit and forging our deep and special future partnership," May said.

As he arrived for the meeting on Friday, Juncker, who sealed the deal with May on December 8 after tense all-night talks, said the British premier had made "big efforts".

But he warned the next stage "would be much harder than the first phase, and the first phase was very hard".

Britain voted to leave the EU in a referendum in June 2016 and is due to end its four decade membership on March 29, 2019.

After months of difficult talks, May and Juncker agreed a deal on the key divorce issues of Britain's exit bill, the future of the Irish border and expatriate rights.

At a meeting without the British premier on Friday, the other EU leaders formally approved negotiating guidelines saying there had been "sufficient progress" in the first phase and that the second phase could begin.

May had on Thursday night addressed her counterparts over dinner and was "clear about wanting to move onto trade talks as quickly as possible" with "ambition and creativity", a British official said.

Leaders said there had been polite applause for May, who came to the summit hours after a humiliating parliamentary defeat over her Brexit plans.

SS