British and European Union negotiators made scant progress towards a deal on future ties in talks this week, they said today.
Both sides also voiced concern that time is running out to reach an agreement before an end-year deadline.
"Those who were hoping for negotiations to move swiftly forward this week will have been disappointed," the EU's chief negotiator, Michel Barnier, told a news conference after two full days of talks in Brussels.
His British counterpart David Frost said a deal on post-Brexit relations was "still possible" and was still London's goal but would not be easy to achieve.
"There are significant areas which remain to be resolved and even where there is a broad understanding between negotiators, there is a lot of detail to work through," Frost said in a statement.
"Time is short for both sides," he added.
After 46 years of membership, Britain became the first country ever to leave the EU on 31 January.
The two are now negotiating a new partnership, to be effective from 2021, on everything from trade and transport to energy and security.
Chambers Ireland has called on businesses to expect a hard Brexit and act accordingly. Chief executive, Ian Talbot, said, "Businesses, large and small, throughout the island must act as though a deal will not be forthcoming. Businesses need to interrogate their supply chains to ensure that they are not over exposed to the disruption in trade that a no-deal Brexit presents."
Disagreements over state aid rules and fishing quotas have so far thwarted a deal, which the EU says must be in the making in time to be approved at a summit of the bloc's 27 national leaders on 15-16 October to enable ratification this year.
Beyond the biggest stumbling blocks, differences also linger in discussions on migration, security, dispute-settling mechanisms, human rights guarantees and other areas.
With the coronavirus pandemic wreaking economic havoc and both sides of the Channel wanting to avoid an even deeper recession, EU sources had been relatively upbeat in recent weeks that an agreement could be reached on time.
Mr Barnier sounded downbeat today, however, saying he was "disappointed and concerned" because British Prime Minister Boris Johnson had told the EU he wanted to speed up the negotiating process over the summer.
"This week, once again, as in the July round, the British negotiators have not shown any real willingness to move forward on issues of fundamental importance for the European Union," Mr Barnier said.
"And this despite the flexibility which we have shown over recent months," he said.
He said negotiations too often appeared to be going backwards this week rather than forwards and so, at this stage, an agreement looked unlikely.
"On the European side, we are very concerned about the state of play in our negotiations. The clock is ticking," Mr Barnier said.
An EU diplomat said few had expected significant progress this month, and there are better prospects for headway to be made in the next round of negotiations, which will be held in London during the second week of September.
Britain today blamed the European Union for holding up progress to secure a post-Brexit trade deal, as the seventh round of negotiations broke up.
Mr Frost said Brussels' insistence that London accept EU state aid and fisheries policy before work on other areas made it "unnecessarily difficult to make progress".
David Frost reiterated that he thought a deal remained possible and was Britain's aim but he warned: "It is clear that it will not be easy to achieve."
The latest talks were "useful but there has been little progress", he added, highlighting continual sticking points on competition rules and fishing rights.
"The EU is still insisting not only that we must accept continuity with EU state aid and fisheries policy, but also that this must be agreed before any further substantive work can be done in any other area of the negotiation, including on legal texts," he said in a statement.
"This makes it unnecessarily difficult to make progress," he added.
Time is running out for both sides to reach agreement, given the need for the deal and legal texts to be scrutinised by member states and ratified by the European parliament.
The next round of talks is scheduled to be held in London in the week of 7 September, with UK officials eyeing the planned October summit as the deadline for a deal.