The EU has warned that Britain is headed for a damaging no-deal Brexit, with London's ideas for solving the contentious issue of the Irish border still unlikely to unlock a deal just six weeks before the leave date.
Addressing EU lawmakers in Strasbourg, European Commission President Jean-Claude Juncker said British Prime Minister Boris Johnson had told him on Monday that London still wanted a deal, but would leave with or without one on 31 October.
"There is very little time left ... The risk of a no-deal is very real," Mr Juncker said, his comments weighing on sterling.
Pro-Brexit lawmakers cheered and applauded in the Strasbourg chamber on Wednesday.
"It's time for a clean-break Brexit," Brexit campaigner Matthew Patten said.
Other pro-Brexit EU deputies tried to shout down pro-EU British colleagues, shouting "You lost!" and "Rubbish!"
A majority of EU lawmakers later voted for an extension to Britain's scheduled departure date in a resolution that is not binding but which has political weight.
EU leaders will meet for a make-or-break summit in Brussels on 17-18 October, just a fortnight before Brexit is due to materialise more than three years after Britons voted to leave.
Britain is not likely to present a complete set of detailed, written proposals of how it would want the text of the existing - but stalled - Brexit deal changed before the end of the month, UK and EU sources said.
"If that is the case, the summit will end with nothing," an EU diplomat dealing with Brexit in Brussels said.
"If there is to be a deal, it must be prepared to a large extent in advance. It is too technical to leave to the leaders at the last minute."
In a worst-case scenario, a no-deal Brexit could mean severe disruption to trade, supplies of medicines, fresh foods and possible public disorder, according to the British government's contingency plans.
Such a sharp break in economic ties, ending four decades of EU membership, "might be the United Kingdom's choice, but never the choice of the EU," Mr Juncker said, highlighting how the bloc wants to avoid blame if Britain crashes out.
Mr Juncker said London must present realistic proposals to replace the Irish backstop arrangement in the Britain-EU divorce agreement, which former prime minister Theresa May agreed with EU leaders but which was rejected by the British parliament.
"I am not emotionally attached to the Irish backstop," Mr Juncker said.
"I have asked the prime minister to make, in writing, alternatives," he added, calling it a safety net to avoid a divided Ireland after Brexit.
The backstop would require Britain to obey some EU rules if no other way could be found to keep the land border between British-ruled Northern Ireland and EU member Ireland invisible.