(Adds Barnier's comments)
BRUSSELS, May 22 (Reuters) - European Union governments agreed a common Brexit negotiating plan on Monday and renewed their insistence that they would not open talks on a post-Brexit trade deal until London agrees to settle what it owes the Union.
Ministers from the 27 other EU states met in Brussels to sign off on a common strategy and mandate the EU executive, in the form of chief Brexit negotiator Michel Barnier, to launch talks on their behalf after Britain's June 8 election. The strategy and mandate were adopted unanimously, officials said.
Barnier said he expected to sit down with British officials for the first time in the week starting Monday, June 19, and to report to EU leaders on the talks during a summit on June 22-23, exactly a year since Britons shocked the Union by voting to leave in a referendum on June 23, 2016.
Several ministers stressed their priorities are to provide legal clarity for EU citizens in Britain before they find themselves living outside the EU in March 2019 and to agree how to calculate what London owes Brussels before departure.
The Union's leaders agreed last month on a phased structure of talks, under which the free trade agreement which British Prime Minister Theresa May wants with the EU would only be discussed after a first phase of talks makes "significant progress" on issues such as citizens' rights and the budget.
"It's clear that in this matter, on the finance issue, if we get stuck then we will not get onto 'phase two', what should come afterwards between the European Union and Great Britain," Luxembourg Foreign Minister Jean Asselborn said on arrival.
His Dutch counterpart Bert Koenders told reporters: "It's very British to know that if you're part of a club and then you leave you have to settle your accounts."
DEAL OR NO DEAL
Barnier's British counterpart, Brexit Secretary David Davis, told a weekend newspaper that his threat to walk out without a deal with the EU was serious. Barnier said that was "not my option" and he did not want to think about such an outcome, which EU officials say would create a chaotic legal limbo.
Deal or no deal, the EU treaty stipulates that Britain will be outside the bloc on March 30, 2019.
May and her Conservative government have said they will meet their obligations but challenge the idea that Britain might have to pay tens of billions of euros to the EU to cover its share of existing financial commitments. Britain wants to launch talks on a future trading relationship as soon as possible.
Barnier said there was no plan to "penalize" Britain and that the two-stage approach, whereby trade talks could start early next year, was needed to avoid confusion. Settling the first phase of talks would "build trust" between the sides.
Several ministers stressed the unity among the 27. Some, including Austrian Foreign Minister Sebastian Kurz, said the other net contributor countries must pay no more into the EU budget after Britain left.
Germany's European Affairs Minister Michael Roth underlined the need to get started to contain the damage from what he said was a "lose-lose situation" for both Britain and the EU.
"We have two years. The clock is ticking," Roth told reporters. "We have to get down to work."
(Reporting by Alastair Macdonald; Editing by Greg Mahlich)