BRUSSELS (AP) -- European Union leaders vowed Saturday to stand shoulder-to-shoulder behind their negotiating team during the divorce proceedings with Britain and warned that demands from British Prime Minister Theresa May will be dealt with "firmly."
The 27 EU leaders in Brussels finalized the cornerstones of their negotiating stance within minutes of starting a short summit, a month after the British leader triggered two years of exit talks on March 29. The negotiations themselves are to open shortly after Britain holds an early election on June 8.
"Guidelines adopted unanimously. EU27 firm and fair political mandate for the #Brexit talks is ready," EU Council President Donald Tusk tweeted.
The leaders say there can't be any discussions on the future relationship between the EU and Britain before some key issues are settled. Those include how much Britain owes the bloc, what to do about the Irish land border with Britain and, Tusk said, making sure the welfare of citizens and families living in each other's nations will be a priority.
The guidelines halted British hopes of having future trade relations being discussed concurrently all through the talks. Tusk said "before discussing the future, we have to sort out our past. We will handle it with genuine care — but firmly."
Some at the summit were already considering how to deal with possible British negotiating tactics.
"Maybe the British government will do its utmost to split the 27 nations and it is trap we need to avoid," said Belgian Prime Minister Charles Michel.
Ever since the June 23 referendum last year in which Britons narrowly voted to leave the bloc, the remaining 27 EU nations have shown a rare exceptional unity. In contrast, citizens in Britain have been divided because of the momentous event looming.
Now, the EU is also intent on making Britain pay the divorce bill, which some EU officials have put as high as 60 billion euros ($65 billion).
"If you are no longer part of a club, it has consequences. A Brexit for free is not possible," Michel said.
To kick off the negotiations, Tusk wants to center on the millions of people living in each other's nations who would be immediately affected.
All sides "need solid guarantees for all citizens and their families who will be affected by Brexit on both sides. This must be the No. 1 priority," Tusk said. Some 3 million citizens from the 27 nations live in Britain while up to 2 million Britons live on the continent, all facing massive uncertainly on such issues as health benefits, pensions, taxes, employment and education.
Tusk said the sustained unity of the 27 will help May since she will have political certainty throughout the talks.
"Our unity is also in the U.K.'s interest," he said. "I feel strong support from all the EU institutions, including the European Parliament, as well as all the 27 member states. I know this is something unique and I am confident it will not change."
Over the past years, the bloc has often been bitterly divided over issues like the financial crisis, the euro debt crisis, bailouts to financially-strapped members like Greece, and how to deal with the hundreds of thousands of migrants entering the bloc.
The 27 EU leaders also acknowledged that Northern Ireland could join the bloc in the future if its people vote to unite with EU member state Ireland.
The two share the same island, and the difficulties of re-establishing a land border once Britain leaves are immense and politically fraught.
Ireland's Europe Minister Dara Murphy told The Associated Press that a statement on the Northern Ireland issue was added to the minutes of the summit, which is being held without Prime Minister Theresa May.
Future relations between Ireland and Britain, including how the border between Ireland and Northern Ireland would work with the U.K. outside the bloc, have emerged as a key problem to be addressed during the Brexit talks.