Britain's chief Brexit negotiator said Thursday it was clear that London will not achieve its goal of striking a preliminary July agreement on the UK's exit from the EU.

Brussels said London is holding out hope one could be reached in September.

"It is unfortunately clear that we will not reach in July the 'early understanding on the principles underlying any agreement'," David Frost said after the latest round of negotiations ended in London.

But both sides agreed on one thing: there had been no movement on the main stumbling blocks to a deal on fair competition guarantees - the so-called level playing field - or on fisheries.

Prime Minister Boris Johnson last month said he wanted British business to know by the end of July whether a deal was within striking distance or if they should start preparing for a messy no-deal split when the post-Brexit transition period ends on December 31.

Since Britain left the bloc in January, talks on the trade agreement and other future ties have all but stalled, with each side accusing the other of failing to compromise before a transition period runs out at the end of this year.

The ongoing talks are aimed at striking a brand new agreement on trade and other areas such as rights to fishing waters and data protection rules.

But months of talks have made little headway because Britain refuses to accept many of the conditions the EU demands for open access to its economic market.

(With input from agencies)