Emmanuel Macron, candidate in France's 2017 French presidential arrives at 10 Downing Street in central London, Britain, February 21, 2017. [Photo/Agencies]

LONDON - French presidential candidate Emmanuel Macron told British Prime Minister Theresa May on Tuesday not to expect any favours from the European Union during Brexit talks, and drew big cheers for his pro-EU message from French nationals in London.

Macron visited May at her Downing Street office and later met Britain's finance minister Philip Hammond, a public relations coup for the young ex-banker at a time when his campaign appears to be losing momentum.

"Brexit cannot lead to a kind of optimisation of Britain's relationship with the rest of Europe. An exit is an exit," he told reporters outside 10 Downing Street after meeting May.

"I am very determined that there will be no undue advantages."

Macron, 39, a former economy minister in Socialist President Francois Hollande's government, is running as an independent. He is due to unveil his detailed programme next week.

The latest polls suggest he and right-wing rival Francois Fillon are tied behind far-right leader Marine Le Pen ahead of the first round of the election on April 23. Polls suggest either man would easily beat Le Pen in the May 7 run-off.

Macron, who did not obtain a meeting with German Chancellor Angela Merkel during a recent visit to Berlin, was keen to improve his standing on the world stage and court voters in London, which has an estimated 200,000 French residents.