European Council President Donald Tusk said Thursday that Britain's Brexit proposals "will not work" as it may risk undermining the EU single market.
Tusk made the statement at a press conference following a two-day informal summit partly focusing on Brexit talks in the Austrian city of Salzburg.
Regarding British Prime Minister Theresa May's Chequers plan for Brexit, Tusk said that "the suggested framework for economic cooperation will not work, not least because it risks undermining the single market".
May defended her Cherquers proposal for Brexit on Wednesday when arriving in Salzburg by saying that "It's the only credible and negotiable plan on the table that delivers no hard border in Northern Ireland and also delivers on the vote of the British people".
According to the proposal, frictionless trade in goods between Britain and the EU could be maintained through a new free trade area.
Tusk hoped that substantial progress over Brexit talks with Britain could be made in October this year.
"The moment of truth for Brexit negotiations will be the October European Council (summit)," Tusk said.
"In October we expect maximum progress and results in the Brexit talks. Then we will decide whether conditions are there to call an extraordinary summit in November to finalize and formalize the deal,"he added.
Should the extraordinary summit take place, it would be on November 17-18, according to Tusk.
In addition, the 27 EU leaders reconfirmed that "there will be no Withdrawal Agreement without a solid, operational and legally binding Irish backstop".
"We continue to fully support (EU chief negotiator) Michel Barnier in his efforts to find such a model," the president said.
