Davis said Prime Minister May will also set out at an EU summit on Thursday her proposals for the rights of the three million EU nationals living in Britain, and one million Britons in the EU, with the British government to publish a detailed offer next Monday.
UK Brexit minister David Davis and EU Commission chief negotiator Michel Barnier will meet at the European Commission in Brussels to formally start the highly anticipated talks that will determine exactly how the divorce will work.
Mr Davis said he was optimistic about the process and the British appeared upbeat about the prospects of trade talks beginning before the final details of divorce proceedings had been agreed.
She said: "During the election I was very clear on the idea of a hard Brexit where we lost out on access to the single market and protection for the rights of Europeans here and our residents".
"It was a mistake for the campaign not to focus more on an area where we have a great story to tell - our record on the economy", he said.
The election results have therefore left Britain in a weaker negotiating position in Brussels, as some European Union leaders fear May's government will be unable to negotiate viable terms on which to leave the European Union at all, meaning the talks could end without any deal. Even if a trade agreement has been sealed, it could be introduced gradually during an "implementation phase" after Brexit.
That left it nearly 2.5 percent lower than an eight-month high hit in May on the view that Prime Minister Theresa May's Conservative party would increase its majority in elections on June 8, giving Britain a strong position to negotiate with the European Union from. -Irish border, and United Kingdom financial commitment, before delving into issues such as trade and security.
European Union diplomats hope this first meeting, and a Brussels summit on Thursday and Friday where May will encounter - but not negotiate with - fellow European Union leaders, can improve the atmosphere after some spiky exchanges.
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Japanese Prime Minister Shinzo Abe has sent a sympathy message to President Donald Trump over the fatal collision involving a U.S. At the same time, I want to express my most heartfelt appreciation to our Japanese allies for their swift support and assistance.
Macron, a committed pro-EU leader and ally of Merkel, also easily won French legislative elections on Sunday, cementing his power base.
Anxious by immigration and loss of sovereignty, Britain voted previous year to end its four-decades-old membership of the 28-country bloc - the first state ever to do so.
Barnier said he hoped the talks, starting nearly a year to the day after a British referendum vote to leave the EU, would "identify priorities and a timetable that would allow me to report to the European Council later this week that we had a constructive opening of negotiations". He said he views the talks with "informed optimism".
May herself will also have a chance to update the other 27 European Union leaders on her Brexit plans at a summit meeting in Brussels on Thursday.
"The best way we can spend this week is to rebuild trust", rather than tackle the big hard issues right at the start, another European source said.
"In the first step, we will deal with the most pressing issues".
The British Chambers of Commerce, the Confederation of British Industry, the EEF, the Federation of Small Businesses, and the Institute of Directors wrote an open letter to the British government, underscoring the "economic benefits" of the single market and the three freedoms (goods/services, capital, and people), as well as the customs union, which enables tariff-free trading.
"If we're going to radically change the way we work together, we need to get there via a slope, not via a cliff edge", he said.