Britain's May sets gracious tone before Brexit briefing

By Alastair Macdonald and Elizabeth Piper

BRUSSELS (Reuters) - Prime Minister Theresa May said on Thursday it was right for EU leaders to discuss Brexit without her over dinner, setting a conciliatory tone before she updates them on Britain's preparations for leaving the bloc.

At the start of a summit when EU leaders will for the first time have dinner without the British prime minister, May sought to reinforce her message that, while still a member, Britain will play a full part in discussions on European Union issues.

Summit chair Donald Tusk said in a tweet May will update the leaders "on Brexit preparations".

But the summit is focused on other matters, including curbing migration from Africa and on building up defences against Russia as Donald Trump prepares to enter the White House with an agenda many Europeans fear may dilute the U.S. military commitment to protect them from Moscow.

"I welcome the fact that the other leaders will be meeting to discuss Brexit tonight as we are going to invoke Article 50, trigger the negotiations by the end of March next year," May told reporters.

"It's right that the other leaders prepare for those negotiations as we have been preparing. We will be leaving the EU. We want that to be as smooth and as orderly a process as possible. It's not just in our interests, it's in the interests of the rest of Europe as well."

An aide to May said she saw the dinner as a sign that EU leaders are "facing up to the reality that the UK is leaving" and getting ready for Britain to trigger the EU treaty article that will start divorce talks.

British ministers have said that after responding with anger to the referendum decision, EU officials are starting to approach some of the most complicated talks in the region since World War Two with a feeling of "mostly friendly regret".

Both sides have given little away as to their negotiating stance, but Britain was warned again on Thursday that finalising a new trade deal with the EU could take 10 years.

IMPATIENT

EU governments have been impatient for May to start a process they see as being held up by divisions in London on what to ask for in a Brexit that even few of its supporters had thought likely before a shock referendum vote in June.

The leaders will end the dinner with a statement saying they are ready to start talks with London and negotiate swiftly, to stick together to preserve the Union and to ensure Britain does not retain EU benefits, for instance on trade access, if it shirks obligations, such as accepting EU migrants.

"They stand ready to start negotiations with the UK as soon as the UK has notified," a draft of the statement said.

It added that the Council of EU leaders would give a negotiating mandate to the EU's executive arm, the European Commission, while ensuring national governments were kept in the loop by officials named by Tusk to sit in on talks run by the commission's negotiator, Michel Barnier.

The European Parliament, which must sign off on any deal, would be kept informed, the draft says -- angering lawmakers who want to be involved directly.

The Parliament's outgoing president, Martin Schulz, who will brief the summit, said he was "really surprised" by the plan.

(editing by John Stonestreet)