European Union diplomats said his aim was to talk up the trade deal in order to entice Britain into accepting it and an Irish border emergency plan - a key sticking point in Brexit talks.
Mr Barnier has asked Brexit Secretary Dominic Raab to provide technical data on how checks and controls along the Irish Sea might work in the event of the backstop coming into play.
For sterling bears finding it increasingly expensive to fund these short bets, some traders said Barnier's comments - indicating a slightly more conciliatory tone rather than a major shift in negotiating stance - were the final straw.
The European Union's Michel Barnier says it's "possible" to get an agreement on Britain's withdrawal from the EU in time for a summit of the bloc's leaders in Brussels from October 18 to 19, but added that a delay into November was also possible.
Progress on the Withdrawal Agreement, which is 80% complete, is being held back primarily by a failure to agree on a backstop solution to avoiding a hard border in Ireland.
He said the two sides would need an agreement by November at the latest if it is to be in place when Britain leaves the European Union as planned on March 29, 2019.
Michel Barnier is refusing to back down on erecting a border in the Irish Sea to avoid a hard border on the island of Ireland, and has publicly asked the British government for data to prove that the checks on goods flowing within the territory of the United Kingdom would be few in number.
The UK Government and politicians from across the spectrum have rejected the EU's vision of a backstop that keeps Northern Ireland under European customs rules.
The UK Government insists that any backstop position should include the UK as a whole.
He told a parliamentary committee that October remains the goal but there was a "possibility it may creep beyond that", Xinhua news agency reported on Thursday.
"The solutions must be workable".
In response to Barnier's latest comments, GBPUSD was barely changed after its Wednesday gains, suggesting the uptrend in the pair that began two weeks ago will likely extend higher.
German foreign minister Maas adds "we are aiming for an ambitious and close relationship with Britian after Brexit both in economic and in security and foreign policy".