The EU's chief Brexit negotiator Michel Barnier | Frederick Florin/AFP via Getty Images | Frederick Florin/AFP via Getty Images Michel Barnier: No alternative to backstop until withdrawal deal ratified EU’s chief Brexit negotiator also says he is ‘not optimistic’ about avoiding a no-deal outcome.

The European Union will not discuss alternative arrangements regarding the Irish border until the U.K. parliament ratifies the Withdrawal Agreement, Michel Barnier has said.

In a piece in the Sunday Telegraph, the EU's chief Brexit negotiator effectively rejected demands for the Irish backstop to be scrapped from the agreement, saying it represents the "maximum amount of flexibility" the bloc could offer.

Barnier said that the EU is prepared to start looking for "alternative arrangements that achieve the same objectives of the backstop" only during a transition period following Brexit, writing: "We are ready to start this work immediately upon ratification of the Withdrawal Agreement, in parallel to finally creating clarity on our future relationship."

British Prime Minister Boris Johnson has called for the backstop — a legal mechanism designed to avoid a hard border between Ireland and Northern Ireland — to be removed from the Withdrawal Agreement.

Barnier also said he is "not optimistic" about the U.K.'s chances of avoiding a no-deal exit on October 31, noting that the prime minister has ruled out asking for a further extension to Article 50.

Johnson announced last week that he would suspend parliament for five weeks until mid-October, narrowing the window for MPs to attempt to block no deal.

Speaking to the Sunday Times this weekend, the prime minister said: "What we need to do is get a deal done, or if we can’t get a deal done then get out of the EU on October the 31st, come what may."