Negotiations over Britain’s exit from the EU will begin on Monday.
Brexit Secretary David Davis and the European Commission’s chief negotiator Michel Barnier agreed during discussions in Brussels on Thursday to start formal talks over the UK’s departure on 19 June.
It had been suggested the start of negotiations could be delayed by the failure of any party to win a House of Commons majority at last week’s General Election.
The Conservatives are still negotiating with the Democratic Unionist Party over whether their 10 MPs will support the Tories’ minority government.
Earlier on Thursday, it was announced the uncertainty in Westminster had pushed back the Queen’s Speech – when the monarch announces the Government’s programme for the parliamentary session – from Monday to Wednesday next week.
But the Government will press ahead with the first round of Brexit talks two days before the official opening of Parliament.
Theresa May’s failure to win a majority at the General Election has led to suggestions her Brexit plan to leave the EU’s Single Market and Customs Union could be altered, while rival parties have demanded involvement in exit talks following the inconclusive result.
Liberal Democrat MP Alistair Carmichael said: “The Conservatives cannot go from weak and wobbly to business as usual in three days. It does not wash.
“If the Government cannot even secure a deal with the DUP, how on Earth can they get a deal with the EU?
“Theresa May must immediately create a cross-party joint Cabinet committee to negotiate Brexit. It is the only way to unite the country and strengthen our bargaining power with the EU.”
The Prime Minister triggered Article 50, the legal process for leaving the EU, on 29 March.
Britain and the EU now have less than two years to conclude exit negotiations before the UK’s departure date at the end of March 2019.
The first round of talks are likely to focus on the UK’s so-called divorce bill, estimated to be as much as €100bn (£88bn), as well as the rights of EU citizens currently living in Britain and UK nationals living on the continent.
The Government are hoping to negotiate a trade deal with the EU within the two-year Article 50 process, but the bloc has warned “significant progress” must be made on divorce talks before a future trade relationship with the UK can be discussed.
The first round of Brexit talks will begin two days before a meeting of EU leaders in Brussels on 22 and 23 June.
The Prime Minister will attend the European Council summit to discuss issues such as migration and security, but will be absent from a dinner when the 27 other national leaders review the start of the Brexit process.
Earlier this week, in a joint press conference with Mrs May, French president Emmanuel Macron claimed the door is “always open” for the UK to remain in the EU before Article 50 negotiations are concluded.