The European Parliament chief on Thursday ruled out any Brexit deal without an Irish backstop but said the EU was willing to revive a proposal that would keep only Northern Ireland in the bloc's orbit to maintain a seamless border on the island of Ireland.

The European Parliament must endorse any Brexit deal agreed between the EU and Britain for it to take effect. British Prime Minister Boris Johnson says his country will leave the EU on October 31, deal or no deal.

The backstop, the key obstacle to a deal, aims to ensure no customs or regulatory controls are imposed on the border between the British-ruled Northern Ireland and EU member Ireland after Brexit. Johnson opposes the backstop, fearing it will trap Britain in a permanent customs union with the EU or else split Northern Ireland from the rest of Britain.

"We want an agreement but we are aware that an agreement without a backstop wouldn't work," the new head of the European Parliament, David Sassoli, told a news conference. "There can't be an agreement without a backstop. There won't be one."

"I would like to stress this point: the United Kingdom hasn't provided any alternatives... anything that has been workable," said Sassoli, who hails from Italy's center-left Democratic Party.

Sassoli said any departure without a deal would only ever be Britain's choice and that the bloc was ready to analyse any concrete proposals from London on replacing the backstop.

"We are willing to go back to the original EU proposal which is that a backstop will only be added for Northern Ireland."

He spoke a day after Britain's Brexit negotiator visited Brussels for a third round of talks with the executive European Commission in two weeks.

More than three years since Britons voted out and with just seven weeks to go, the British government and parliament are locked in conflict over Brexit, with possible outcomes ranging from leaving without a deal to holding another referendum.