British Prime Minister Boris Johnson and EU chief Ursula von der Leyen on Saturday asked their negotiators to "work intensively" to overcome differences to secure a post-Brexit free trade deal. 

The two leaders spoke via video-link after the latest negotiations between London and Brussels -- the last scheduled round following months of talks -- ended Friday with both sides saying significant obstacles to an agreement remained. 

"They instructed their Chief Negotiators to work intensively in order to try to bridge those gaps," Johnson's office said, noting they had "agreed to speak on a regular basis on this issue".

"They endorsed the assessment of both Chief Negotiators that progress had been made in recent weeks but that significant gaps remained, notably but not only in the areas of fisheries, the level playing field, and governance," the statement added.

Britain formally left the European Union in January but has remained bound by most of the bloc's rules during a transition phase that ends on December 31.

British and EU negotiators said Friday the months of discussions about a future trade deal remained deadlocked on key areas, with London urging Brussels to give ground to avoid a damaging "no-deal" at the end of the year.

Both sides have pinpointed a European summit on October 15 as the latest an agreement could be reached for it to be ratified in time for it take effect at the end of December.