The fourth round of Brexit talks has been delayed by a week to 25 September, the Government has confirmed.
A spokesperson said “both sides” had agreed to push back the date to give negotiators “flexibility” to make progress at the current stage.
It follows reports that the date was changed to accommodate a major speech on the subject by Theresa May, hinted at for 21 September.
European Parliament Brexit coordinator Guy Verhofstadt predicted the postponement, speculating Mrs May was planning on making an “important intervention”.
Downing Street declined to comment on the claims but Whitehall sources insisted the initial date set for the talks, 18 September, had only been pencilled in and was subject to agreement.
It means the next round of talks will now come less than a month before a crunch EU summit on 19 October, when the remaining 27 member states will meet to decide if enough progress has been made to begin negotiations on a future UK-EU trade partnership.
But figures in Brussels are said to be frustrated at the lack of progress on issues including the Irish border, citizens’ rights and the ‘divorce bill’.
One MEP warned Mrs May would be “out of her depth” if she took up an invitation to address the European Parliament.
And Mr Verhofstadt said of progress in the Brexit talks: “At the moment, everyone can see that isn’t the case.”
Manfred Weber, head of the parliament’s largest political group, also commented: “It seems to be that Great Britain is still thinking that they can follow the full cherry-picking approach. I think that will not work.”
The UK is pushing to move to continuous rolling talks to solve the deadlock.
It comes after Chancellor Philip Hammond revealed the Treasury was preparing for a ‘no-deal’ outcome on Brexit.
Speaking about customs operations at UK ports, he said: “We recognise that timescales are very challenging and in a no-deal scenario, not everything we would want to put in place will be in place on day one.
“But we will have a working system in place from day one.”