LONDON (REUTERS) - Britain's minister for leaving the European Union said on Saturday (April 29) the country was gearing up for the most complex negotiations "in our lifetimes" after the European Union outlined its tough approach to Brexit talks.

Earlier in the day, EU leaders endorsed stiff divorce terms for Britain and warned Britons to have "no illusions" about swiftly securing a new relationship to keep their access to EU markets.

And while British Prime Minister Theresa May dined with EU Commission President Jean-Claude Juncker on Wednesday in a bid to warm ties before talks start, David Davis, the minister responsible for Brexit, said negotiations would be hard.

"Both sides are clear - we want these negotiations to be conducted in the spirit of goodwill, sincere cooperation and with the aim of establishing a close partnership between the UK and the EU going forward," Davis said in a statement in response to the EU's Brexit guidelines.

"But there is no doubt that these negotiations are the most complex the UK has faced in our lifetimes. They will be tough and, at times even confrontational."

Davis added that there were people in Europe who opposed the aims of the talks, and "people at home trying to undermine them."

Britain is set for a national election on June 8 as Prime Minister May seeks to strengthen her hand domestically before beginning negotiations with the EU.

May started the formal process of leaving the EU at the end of March, starting a countdown of two years for the terms of departure to be agreed.