Donald Tusk has been accused of treating the Prime Minister in a "sexist and patronising" way after he warned her not to become "emotional" over Brexit talks.
On Wednesday Theresa May launched a blistering attack on the EU for trying to interfere in the election and "run us over" in Brexit talks.
#Brexit talks difficult enough. If emotions get out of hand, they'll become impossible. Discretion, moderation & mutual respect needed.— Donald Tusk (@eucopresident) May 4, 2017
Mr Tusk, the President of the European Council, warned that Brexit negotiations risk becoming "impossible" as he called for "discretion, moderation and mutual respect".
His message also appeared aimed at Jean-Claude Juncker, the President of the European Commission, after a scathing account of a meeting he had with Mrs May was leaked to the German press.
Mr Tusk said: "These negotiations are difficult enough as they are. If we start arguing before they even begin, they will become impossible.
"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.
At stake are the daily lives and interests of millions of people on both sides of the Channel. #Brexit— Donald Tusk (@eucopresident) May 4, 2017
"We must keep in mind that in order to succeed we need today discretion, moderation, mutual respect and a maximum of goodwill."
Iain Duncan Smith, the former Conservative leader, said: "We could all do without the patronising finger-wagging of unelected politicians in Brussels."
Andrew Bridgen, a Tory candidate, described the comments as "sexist, patronising and inaccurate".
He said: "It's a sign of desperation, the EU would far rather they were negotiating with a weak leader like Jeremy Corbyn than a strong leader like Theresa May."
In 2011 David Cameron, the former Prime Minister, was accused of sexism after he told a female Labour MP to "calm down dear" in the Commons.
It came as the European Union threatened to force clearing houses - one of the most lucrative financial sectors of the City - to relocate from London to Europe. Philip Hammond, the Chancellor, warned that the move risked undermining growth, investment and the financial stability of both Europe and the City.
Mr Hammond said: “We approach the Brexit negotiations with a spirit of goodwill and we will consider any EU proposal before we leave on its merits. "But we should be careful of any proposals which might disrupt growth, raise the cost of investment in Europe and the UK or weaken financial stability."
His intervention came after the European Commission's chief spokesman accused Mrs May of "excited" electioneering. Magaritas Schinas also suggested that the commission is too "busy" to concern itself with Mrs May's comments.
He said: "We are not naive, we know that there is an election taking place in the United Kingdom. People get excited whenever we have elections.
"We have too much to do on our plate. So, in a nutshell, we are very busy. And we will not Brexitise our work. "To put it in the words of an EU diplomat, the 30-minute slot that we are going to devote to Brexit per week, for this week it's up."