The European Union's Brexit negotiator Michel Barnier told Britain on Wednesday that the sooner it agrees on divorce terms the sooner it can start talks on a future trade deal.
"The sooner we agree the principles of an orderly withdrawal, the sooner we can prepare our future relations in trade," he told the European Parliament in Strasbourg.
"A free and fair trade agreement but also in security and defence," he told MEPs as they prepared to vote on the parliament's "red lines" for the coming two years of Brexit talks.
France's Barnier added that as the first EU institution to take a formal position on British Prime Minister Theresa May's letter triggering Brexit last week, parliament would set the "tone" for the negotiations.
The EU has rejected May's call in her letter for talks on the terms of the divorce and on a future trade deal to be held in parallel.
Barnier said Britain had to agree on terms including its exit bill, the rights of EU citizens living in Britain and the border in Northern Ireland before moving on to life after Brexit.
"We are not proposing this to be tactical or to create difficulties for the UK. It is necessary for the chances of reaching a deal in two years which is very short," he said.
He warned, however, that the "devil is in the details".
Barnier, a former European Commissioner and French minister, also urged the remaining 27 EU countries to stay united during the Brexit negotiations amid fears Britain could try to play on divisions.
"If the union is disunited we risk that there is no deal," he said.