0446 GMT December 13, 2019
Barnier insisted the agreement's most contentious element, a so-called backstop mechanism to keep the Northern Irish border open in all post-Brexit circumstances, must remain in place, AFP reported.
"The backstop is the maximum amount of flexibility that the EU can offer," Barnier wrote in the Sunday Telegraph newspaper, following what he called "intense discussions" among member states.
He added he was "not optimistic" of avoiding Britain crashing out of the European Union without an agreement on October 31.
The stance is an apparent setback for British Prime Minister Boris Johnson, who since taking power in July has called for the backstop to be scrapped.
Johnson has insisted the country must depart the bloc with or without a deal on the latest delayed deadline in order to honor the 2016 referendum which saw 52 percent of Britons vote to leave.
His bid to reopen the agreement struck with Brussels by predecessor Theresa May was encouraged by recent meetings with German Chancellor Angela Merkel and French President Emmanuel Macron.
The British premier said in a Sunday Times interview he saw "some very interesting signs of progress in our conversations".
However he conceded: "There's a good chance we'll get a deal and there's a good chance that we won't."
Johnson stoked intense controversy and protests Saturday across Britain after announcing Wednesday he had instructed Queen Elizabeth II to suspend Parliament in the final weeks before Brexit.
The move was widely seen as a bid to limit the time his opponents will have to thwart a no-deal departure from the EU.
Thousands took to the streets of towns and cities across the country to decry the move to close Parliament – known as proroguing – from mid-September until October 14.
Organizers using the slogan #StopTheCoup claimed as many as 100,000 people turned out in London.
MPs from across the political spectrum have vowed to introduce legislation blocking a no-deal exit as soon as they return to Parliament from a six-week summer recess on Tuesday.
"We have simply got to stop us leaving without a deal," Keir Starmer, Brexit spokesman for the main opposition Labour Party, told the BBC on Sunday.
He added the proposed law would "require an extension" to Britain's departure date.
In response, Johnson's government is reportedly considering advising the Queen not to give royal assent to any bill passed by the rebels, an unprecedented step in modern times.
Johnson may also sanction potentially more than a dozen Conservative lawmakers poised to vote against the government this week by throwing them out of the parliamentary party, according to reports.
But leading Tory rebel David Gauke, a senior minister until recently under May, insisted Sunday that "the national interest has to come first".
Johnson's decision to suspend Parliament also sparked several legal challenges that will be heard this week.
A Scottish judge is expected to consider a legal review against the suspension on Tuesday.
A London court will hear another bid to block the move, supported by former Conservative prime minister and staunch Brexit opponent John Major.
Meanwhile, the government continues to prepare for a possible no-deal Brexit.
Gove, charged with preparing for the scenario, said Sunday that some food prices would likely increase, while others would go down.
Gove also insisted that EU citizens' freedom of movement would end on October 31, despite a Sunday Times report that the plan had been postponed on the advice of lawyers.