Verhofstadt and the UK's Brexit minister David Davis agreed that there was a window "of more or less 14, 15 months" for negotiations on Britain's departure from the European Union.

"We agreed ... on the need for this process to start as early as possible and need to be finished in any case before the next European elections (in May 2019)," the European Parliament's Brexit negotiator warned said after the talks in Strasbourg, France.

"It's going to be a period that is very intense," Verhofstadt warned, predicting that formal negotiations would likely start in May 2017, two months after British Prime Minister Theresa May triggers the two-year divorce process, which she has indicated will happen next March.

'No special deal'

Verhofstadt said he also told Davis that the European parliament would not accept Britain cherry-picking the best parts of EU membership, by trying to keep access to the single market while limiting freedom of movement for EU citizens.

Britain says it wants to cut EU migrant numbers but retain access to Europe's single market.

MEPs must then formally give their consent for any deal and that would take several months from late 2018, Verhofstadt said.

The former Belgian prime minister was joined for the talks by Manfred Weber, a conservative ally of German Chancellor Angela Merkel.

Weber voiced impatience with a lack of clarity from May, adding: "I see a British government that keeps saying where it wants to cooperate closely and not how it wants to leave the European Union."

"Unfortunately I haven't heard anything new from David Davis today. For us it's clear: the four fundamental freedoms are not negotiable," he said, referring to free movement of goods, workers, services and capital.

Davis hopeful

Davis described Tuesday's meeting as "great fun" and "very useful."

"My view is that we can get an outcome here which will be in the interest of the European Union and in the interest of Britain and will meet the requirements of the referendum," he told the BBC.

On Monday, Davis met the European Commission's top negotiator Michel Barnier in Brussels for a "courtesy coffee."

The pair both insisted the meeting did not mark a formal start to negotiations, saying that would have to wait until Britain formally triggers the exit process.

Some analysts believe Britain may request a transitional arrangement to meet the 2019 deadline, with a full Brexit coming later.

May must also wait for an appeal in the British Supreme Court over whether the UK's parliament must approve the process to trigger Brexit. That ruling is due in early 2017.

mm/kl (AFP, Reuters)