Following discussions in Brussels on Thursday, the offices of Brexit Secretary David Davis and the European Commission's chief negotiator Michel Barnier released a joint statement to confirm the date.
"We all have an interest.in keeping them as close as possible to the European Union, because Britain is an important country, vital to the EU in the security and foreign policy realm, and naturally also a part of the European market", he said.
Top negotiators will on Monday discuss Britain's financial obligations to the European Union as the long and complicated process of the United Kingdom leaving the bloc finally gets underway.
The first round of formal negotiations on Britain's withdrawal from the European Union will begin on June 19, it has been confirmed.
"There is a unity of goal among people in the United Kingdom", May said following a meeting with French President Emmanuel Macron in Paris.
But with so much at stake for Britain and its $2.5 trillion economy, pressure was mounting on May from within and without her party to heed other voices.
In this grab taken from video, Britain's Prime Minister Theresa May speaks in the House of Commons, London, during its first sitting since the election, Tuesday June 13, 2017.
The report cited unnamed sources, and the finance ministry declined to comment.
The Conservatives have 317 MPs while the DUP have 10.
That problem is compounded by the fact that May has yet to strike a deal with Northern Ireland's Democratic Unionist Party that would give her the extra votes in Parliament she needs for a working majority.
"The prime minister has totally ignored the will of those people in terms of Brexit".
An election in March saw the Protestant, pro-British DUP finish narrowly ahead of Catholic socialists Sinn Fein.
While the DUP are deeply eurosceptic, they have balked at some of the practical implications of a so-called hard Brexit - including a potential loss of a "frictionless border" with the Republic of Ireland - and talks will touch on efforts to minimise the potential damage to Northern Ireland. May has not yet responded to a proposal from some Conservatives for business groups and lawmakers from all parties to agree a national position on Brexit.
However, a soft Brexit would be a "daft" option, a political analyst told CNBC on Wednesday.
May faces a hard balancing act.
Yet many of her lawmakers and party members favour a sharp break with the European Union - a sign of the divisions over Europe that helped sink the premierships of May's predecessors Margaret Thatcher, John Major and Cameron. But there is also incredulity that the British government is preparing to go into the talks with a hard-line negotiating position when it can not command a majority at home. The European Parliament's Brexit coordinator, Guy Verhofstadt, struck a harsher tone: Britain, he said, could change its mind, but it would be poorer.
Speaking as he arrived for a meeting of European Union finance ministers in Luxembourg, he said: "As we go into that negotiation, my clear view - and I believe the view of the majority of people in Britain - is that we should prioritise protecting jobs, protecting economic growth and protecting prosperity as we enter those negotiations and take them forward".