Tusk is due to meet Theresa May, who is also due to give a major speech next week setting out the U.K.'s position | John Thys/AFP via Getty Images Donald Tusk: UK Brexit position is ‘pure illusion’ European Council president says EU27 would resist British attempts to cherry-pick benefits of single market.

The U.K.'s negotiating position on its relationship with the EU post Brexit is based on "pure illusion," according to European Council President Donald Tusk.

Speaking at a press conference following a summit of EU leaders in Brussels, Tusk was dismissive of the agreement reportedly reached among senior U.K. Cabinet ministers at a meeting Thursday to get behind a position of "managed divergence" in some sectors of the single market but not others.

“If the media reports are correct I’m afraid that the U.K. position today is based on pure illusion. It looks like the cake philosophy is still alive,” he said, referring to the British fondness for having cake and eating it too. “From the very start there has been a key principle, there can be no cherry-picking and no single market à la carte,” Tusk added.

The Council president is due to meet Theresa May in London on Thursday. The British prime minister is also due to give a major speech next week setting out the U.K.'s position, although the date of the speech has not been fixed.

Tusk said that the Council would finalize guidelines for negotiations on the future relationship in March, whether Britain was prepared for the next phase or not.

"Our intention is to adopt these guidelines, whether the U.K. is ready with its vision of our future relations or not, " he said. "Naturally it would be much better if it were. But we cannot stand by and wait. I hope to have some more clarity about the U.K.'s plans next week, when I meet Prime Minister May in London."

Commission President Jean-Claude Juncker, who was sharing the platform, said he could not better Tusk's criticism of the British position. “The president of the Council was offering you a headline for tomorrow,” he told reporters.

Juncker had earlier joked, "Where is Mr. [David] Cameron now?" when discussing the former U.K. prime minister's objection to his appointment to the top Commission post.

“I’ve heard some rumors he is in a quite comfortable position,” Tusk responded.

Juncker replied by noting Cameron wanted to put him in the same “comfortable position."

This article has been updated.