The UK is engaged in an "internal battle" over its Brexit position, the European Parliament's negotiator has said.
Talks are not going well and Britain's position is not clear enough, Guy Verhofstadt added.
He warned the outcome needed to be positive for both sides as the UK and EU gear up for a fourth round of negotiations next week following Theresa May's major speech in Florence on Friday.
Mr Verhofstadt said: "We feel, hopefully I am wrong, that we don't receive always a clear UK position.
"There is still internal battle in UK about what is their position, what they want.
"For us there was not a problem, there was a single market, a customs union, no one was complaining about that, but by leaving all these points come back."
The British Government has said it is working together to deliver Brexit and seeking a deep and special partnership with the EU.
Boris Johnson's Brexit intervention in a Telegraph article on Saturday has overshadowed the Prime Minister's three-day visit to the US and Canada ahead of her crucial Brexit speech in Florence.
The Foreign Secretary was forced to deny he was planning to resign, while Mrs May faced calls for her to sack him from her Cabinet.
But the threat of a damaging outcome to the bust-up receded as Mr Johnson backed away from his key demand that the UK should cease payments to the EU after the date of Brexit in 2019.
The Government has also faced criticism from a number of pro-European Conservative MPs for its handling of a key piece of Brexit legislation.
Mr Verhofstadt, a former Belgian prime minister, is on a two-day fact finding mission to Northern Ireland and the Republic.
He is the link man between the EU negotiating team and the European Parliament.
On Wednesday he visited the 220-acre dairy farm of the Hughes family, which straddles Co Armagh in Northern Ireland and Co Monaghan in the Republic.
Northern Ireland is the only part of the UK which will have a land frontier with an EU state after Brexit in March 2018.
Mr Verhofstadt said the UK had yet to make a "concrete proposal" on resolving the border question.
Asked about the general state of negotiations he said: "For the moment things are not going very well."