The UK has demanded that the EU allow the delivery of COVID-19 vaccines it has ordered as tensions over a possible ban on EU-manufactured shots mounted, but Brussels put the blame on AstraZeneca.
"The UK is not to blame. The EU is not to blame," said an EU official. "It's about everyone finding agreement with a company that has been over-selling its production capacity. AstraZeneca has to deliver doses to its EU customers."
After falling far behind post-Brexit Britain and the United States in rolling out vaccines, the EU's leaders are due to discuss imposing a ban on vaccine exports to Britain at a summit on Thursday.
British Prime Minister Boris Johnson is expected to speak to the EU's most powerful leaders, German Chancellor Angela Merkel and French President Emmanuel Macron, in a bid to get the bloc to steer away from bans.
"There will continue to be some robust conversations with the European Union about the importance of no such blockings happening," Helen Whately, a junior health minister, told LBC radio. "It's really important that companies are able to fulfil their contractual obligations."
Britain, which exited the EU's orbit on December 31, has repeatedly cautioned the EU that breaking contract law could have grave consequences but has not yet specified what those consequences would be.
AstraZeneca has told Brussels that the UK is using a clause in its supply contract that prevents exports of its vaccines until the British market is fully served, EU officials said.
While France, Germany and Italy broadly support tighter export curbs on those who do not reciprocate, countries including the Netherlands, Belgium and Ireland are more cautious about cutting off the UK.
The EU has so far blocked one shipment of vaccines to Australia.
An EU official told Reuters on Sunday that the bloc was rebuffing British government calls to ship AstraZeneca COVID-19 vaccines produced in a factory in the Netherlands.
"The Brits are insisting that the Halix plant in the Netherlands must deliver the drug substance produced there to them. That doesn't work," the official told Reuters.
The Leiden-based plant, run by sub-contractor Halix, is listed as a supplier of vaccines in both the contracts that AstraZeneca has signed with Britain and with the European Union.
"What is produced in Halix has to go to the EU," the official added.
AstraZeneca has not yet sought approval in the EU for Halix, but the official and a second EU source said the request was on its way. Without regulatory approval, vaccines produced at Halix cannot be used in the EU.
As of March 20, the UK had administered nearly 44 vaccines for every 100 people, whereas the EU had administered nearly 13 shots per 100 people, according to public data compiled by Our World In Data website.