London (CNN) The United Kingdom's position on Brexit is based on "pure illusion," European Council President Donald Tusk told reporters in Brussels after a meeting of EU leaders.

His comments Friday came a day after UK Prime Minister Theresa May and senior Cabinet ministers spent hours at her official country retreat hammering out London's position in future Brexit negotiations in the face of deep divisions within her Conservative Party.

May is expected to set out her vision for Britain's future trading relationship with the European Union in a speech next Friday. But Tusk's remarks raise questions over how well it will go down in Brussels.

"I'm afraid that the UK position today is based on pure illusion. It looks like the 'cake philosophy' is still alive," Tusk said. "From the very start, there has been a key principle of the EU 27 members that there can be no cherry-picking and no single market à la carte."

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Tusk has previously accused May of holding a philosophy of "having her cake and eating it" over Brexit by trying to keep the benefits of EU membership without having to follow its rules.

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