Donald Tusk, the President of the European Council, leaves after meeting Britain's Prime Minister, Theresa May inside 10 Downing Street, in central London
BRUSSELS (Reuters) - Britain's looming negotiations with the European Union on exiting the bloc are already very tough and will become "impossible" if emotions are allowed to run unchecked, the chairman of EU summits said on Thursday.
Donald Tusk's warning followed comments by British Prime Minister Theresa May on Wednesday that some European politicians and officials were seeking to affect the outcome of Britain's election on June 8.
"These (Brexit) negotiations are difficult enough as they are. If we start arguing before they even begin, they will become impossible," Tusk said in a statement read out after a meeting with Norwegian Prime Minister Erna Solberg.
"The stakes are too high to let our emotions get out of hand. Because at stake are the daily lives and interests of millions of people on both sides of the Channel," said Tusk, who heads the European Council that groups EU national governments.
Discretion, moderation, mutual respect and a maximum of good will were required to succeed, said Tusk, a former Polish prime minister who will play an important role in the negotiations.
Earlier the European Commission, the EU's executive arm, said it had no opinion on May's accusation about meddling.
"We are not naive. We know there is an election taking place in the United Kingdom, people get excited whenever we have elections," Commission spokesman Margaritis Schinas told a news briefing.
Last weekend a German newspaper gave a damning account of a dinner last week between May and European Commission President Jean-Claude Juncker, reporting that he had told May that Brexit could not be a success.
Irish Prime Minister Enda Kenny told a Montreal news conference he regretted the way the remarks had been reported.
"This is not a helpful situation but, be that as it may, it's happened ... the issues that concern the European Union, of which we are a member, will not change," he said after talks with Canadian Prime Minister Justin Trudeau.
Kenny said he expected May to "have a very clear and a very strong hand" domestically after the June 8 election, allowing her to draw up her own mandate for the Brexit negotiations.
May, whose Conservative Party has a double-digit lead over the main opposition Labour Party in opinion polls, initially dismissed the German report as "Brussels gossip" before making her accusation of EU interference in the election.
The Brexit negotiations are expected to begin after the election.
(Reporting by Francesco Guarascio and Philip Blenkinsop in Brussels and David Ljunggren in Ottawa; Editing by Gareth Jones)