The EU insists that AstraZeneca made different and contradictory promises to Brussels and to the UK in their respective contracts, signed last year.
An EU diplomat told the BBC earlier this month: “AstraZeneca appears to have promised the UK priority for the first X million doses – using production facilities in the EU, as well as the UK. This doesn’t add up. Though this isn’t the UK’s fault.”
Tensions between the EU and AstraZeneca heightened in January when Belgian authorities inspected a factory at the request of the European Commission.
Daniel Boffey, The Guardian’s Brussels bureau chief, outlined the row on the Today in Focus Podcast in February.
He said: “The chief executive of AstraZeneca did an interview in January, and he said there was a filtering problem.
“Since then, Belgian authorities have gone into the plant, this is how toxic it is, to see if AstraZeneca is lying or not.
“The officials went in, then they came out and said ‘there is a production problem’ – they talked about there being a lack of raw materials.”
When asked how the EU reacted to AstraZeneca’s claims of short supply, Mr Boffey replied: “Blind fury.”
In return, the UK Government will agree to forgo some long-term supplies of the AstraZeneca vaccine that had been due to be exported from a factory in Holland run by the company’s subcontractor Halix.
Top diplomatic sources told The Times that the behind-the-scenes talks had helped restore trust despite rising tensions in public rhetoric.
One EU diplomat said: “For us it was very significant that Johnson did not use Frost but instead went through the Foreign Office.
“It showed that he was really serious about finding a compromise and trying to build trust.”