The document was released before European affairs ministers were on Monday due to give Michel Barnier a mandate to negotiate Britain's exit from the bloc.
The document was released before European affairs ministers were on Monday due to give Michel Barnier a mandate to negotiate Britain's exit from the bloc on behalf of the remaining 27 member states.
"Mr Barnier specified that the negotiations per se would start as soon as the negotiating mandate was adopted by the Council," according to the minutes of a European Commission meeting held in early May.
"But since a general election had been called for 8 June in the United Kingdom, they would not in fact be launched before mid-June," he was reported to have said during the meeting of the EU executive.
"He hoped that after the British legislative elections the UK's internal political climate would be more conducive to reaching agreement," according to the document.
Barnier conceded that settling Britain's outstanding financial commitments to the EU would be "one of the most difficult" in the negotiations.
"Should there be no agreement on this point, he believed that the risk of failing to reach an agreement on an orderly withdrawal of the United Kingdom would become real," according to the minutes.
None of the remaining 27 states would want to contribute more to the multi-annual budget or receive less in project funding under the framework.
"It was therefore necessary, during the first phase of negotiations, to agree with the United Kingdom on a clear method for calculating its obligations," it said.
Brussels estimates Britain may have to pay 60 billion euros to meet financial commitments from its four-decade membership.
Barnier, a former European commissioner and French government minister, earlier said there was no set sum but that it would be calculated using a "methodology".
Brussels has also set a top priority in determining the fate of EU nationals in Britain and British nationals in the bloc as well as in finding a solution for the UK's border with Ireland.
It wants an agreement on the three main points before a second phase of negotiations focused on the framework of future EU-British relations, particularly a post-Brexit trade deal and transitional arrangements.
Barnier outlined a provisional timetable: an agreement on the first phase between October and December 2017, then a launch of the second phase between December 2017 and spring 2018, then finalisation of a Brexit deal towards October 2018.
The aim would be to have the ratification process for the deal completed by March 2019.