Prime Minister Boris Johnson is expected to ask European leaders this week to dismiss any proposals to block coronavirus vaccine exports to the UK.
Here, the PA news agency looks at how the political row has unfolded.
– What is the latest from the EU?
European Commission president Ursula von der Leyen threatened to block exports of jabs from the EU to countries with higher vaccination rates that do not offer reciprocal supplies of vaccine.
Under pressure over the bloc’s relatively poor vaccine rollout, she ramped up the rhetoric this weekend, saying the EU has the power to “forbid” exports, adding: “That is the message to AstraZeneca.”
– Why have these proposals been put forward by the EU?
The warning from the EU reflects growing frustration on the continent that the bloc is not getting the supplies it expected from AstraZeneca.
But the British-Swedish manufacturer has previously maintained that because the bloc signed its contract later than the UK, EU manufacturing facilities were still catching up.
– How could this affect the UK’s vaccine supplies?
Around 10 million doses of vaccine, mainly the BioNTech/Pfizer jab, have crossed the English Channel to the UK, but Brussels has complained that no AstraZeneca doses have been sent in the other direction.
Reports have suggested the latest focus of the row is on AstraZeneca vaccines produced in the Halix plant in the Netherlands, with officials arguing they should be kept for the EU rather than allowed to be exported to the UK.
– How is the rollout progressing in the EU and UK?
Just over 10% of adults have received a first dose of a coronavirus vaccine across the EU, according to the European Centre for Disease Prevention and Control, while in the UK, the figure is now over 50%.
– What has the UK said about the row?
Defence Secretary Ben Wallace hit back on Sunday by warning that the manufacture of the Pfizer vaccine depends on supplies from the UK, amid reports its production requires lipid ingredients shipped from Yorkshire.
He told BBC One’s The Andrew Marr Show: “The grown-up thing would be for the European Commission and some of the European leaders to not indulge in rhetoric but to recognise the obligations that we all have.”
– Have there been other disputes over vaccines?
In January, the EU briefly attempted to trigger Article 16 of the Northern Ireland Protocol of the Brexit Withdrawal Agreement to impose controls on vaccines.
But Brussels swiftly backtracked after coming in for widespread criticism over the move from London, Dublin and Belfast, which came as EU chiefs faced increasing pressure over delays to the rollout of its vaccination programme.