Boris Johnson, British prime minister, will this week urge EU national capitals to veto a suggestion from Brussels that would block AstraZeneca vaccine exports to the UK and push post-Brexit relations to a new low.

London has laid claim to millions of doses of the Oxford/AstraZeneca Covid-19 jab produced at a Dutch factory, sparking a fierce battle with the European Commission, which says they should be used in the EU.

European heads of government are preparing to decide at a summit beginning on Thursday whether to press ahead with a threat to stop exports of the AstraZeneca vaccine to the UK from the Halix site in the Netherlands. 

British officials said Johnson would call EU counterparts ahead of the leaders’ online meeting, and that Emmanuel Macron, French president, and Angela Merkel, German chancellor, were likely to be on his list.

An EU official retorted that the bloc was “aware of the active campaign by the UK government to lobby certain member states”, citing Belgium, the Netherlands, France and Germany as examples.

The official added: “As in the past, seeking division among the member states will not succeed.”

Ursula von der Leyen, European Commission president, floated the idea of tougher controls on EU jab exports to vaccine-producing countries last week, in a move viewed to be aimed at London.

“We have the option of banning a planned export,” she told Germany’s Funke media group over the weekend. “That’s the message to AstraZeneca: you must fulfil your contract with Europe first before you start delivering to other countries.”

Johnson, who on Sunday celebrated a daily record of 844,285 first and second vaccinations, fears a cross-Channel dispute could spark vaccine protectionism more widely across the globe. The EU accuses the UK of hoarding supplies.

Ben Wallace, UK defence secretary, told the BBC’s Andrew Marr programme that trying to “build walls around this would only damage both EU citizens and the United Kingdom”.

While the European bloc has exported more than 10m doses of various jabs to Britain over the past two months, it has received none in return. 

Frustration with London has mounted in European capitals as the UK’s immunisation drive has benefited from smooth AstraZeneca supplies, while the company has slashed early supply targets in its contract with the EU for up to 400m doses.

“We need to have the principle of reciprocity between countries, and proper proportionality,” Stella Kyriakides, EU health commissioner, told the Financial Times in a video interview. “This is something that will be discussed with the leaders at the summit . . . and it is at that level that decisions will be taken.” 

London has insisted its deal with AstraZeneca to supply the UK with 100m doses gives it first call on production from EU plants as well as British factories.

But the EU is equally adamant that it is entitled to both AstraZeneca supply from Europe and a share from two UK factories also named as production sites in the contract the European Commission signed with the company in August.

The UK did an initial deal with the company several months earlier. 

The EU idea of tighter export controls has divided the bloc’s member states, with countries including the Netherlands and Belgium — both coronavirus vaccine producers — worrying about the risk of disrupting global supply chains. 

Johnson has already spoken to Mark Rutte, Dutch prime minister, and Alexander De Croo, his Belgian counterpart, in an effort to head off any EU summit decision to block shipments.

One Dutch official urged the UK to reach a deal with the commission and AstraZeneca in order to avoid a “lose-lose scenario”.

While the UK has not delivered finished vaccines to the EU, it has previously supplied crucial raw materials needed for the pioneering BioNTech/Pfizer mRNA vaccine made in the bloc. 

A main focus of the EU-UK dispute is a stockpile of unknown size of the AstraZeneca vaccine’s active ingredient produced in the Netherlands by Halix, a subcontractor, both UK and European officials say.

The factory does not have regulatory approval to supply the EU, even though it was named as one of the bloc’s two main sources of production in the European Commission-AstraZeneca contract more than six months ago. 

Kyriakides said the ball was “firmly in AstraZeneca’s court” to supply the data needed for authorisation by the European Medicines Agency. She added that — if all went smoothly — the plant could start to deliver to the EU before the end of the month. 

AstraZeneca has previously said it expected to win EU regulatory approval for the Halix factory soon, and added that the timeline is “entirely as expected”. It did not comment on the UK’s claim to the Halix supply. 

Pascal Soriot, AstraZeneca’s chief executive, has said that the overwhelming majority of its vaccine produced in the EU stays in the bloc.