British Prime Minister Boris Johnson has rejected the possibility the UK could engage in a tit-for-tat vaccine export war with the European Union after it threatened to halt supplies during a row with AstraZeneca.

Mr Johnson said that Britain does not believe in engaging in "blockades of any kind", as he signalled tensions could be thawing during talks with the bloc.

Under pressure over the pace of its rollout and embroiled in a row with pharmaceutical giant AstraZeneca over supplies, EU chief Ursula von der Leyen threatened to halt vaccine exports.

But Mr Johnson told a Downing Street press conference: "We'll continue to work with European partners to deliver the vaccine rollout.

"All I can say is we in this country don't believe in blockades of any kind of vaccines or vaccine materials.

"It's not something that this country would dream of engaging in and I'm encouraged in some of the things I've heard from the continent in the same sense."

Diplomatic efforts have tried to ward off a possible ban on vaccine exports.

Across the EU, just over 10% of adults have received a first dose of a Covid-19 vaccine but in the UK the figure is over 53%.

The government did not deny reports that AstraZeneca vaccines manufactured at the Halix facility in the Netherlands could be shared with the EU to prevent an export ban.

Former ambassador to the EU Sir Tim Barrow is believed to be among the advisers dispatched to Brussels to try to negotiate a solution.