France and Germany have threatened legal action against the Anglo-Swedish pharmaceutical company AstraZeneca in the row over a shortage of coronavirus vaccine in the EU.

Talks between the European commission and the vaccine supplier are continuing over the lack of supply, with Brussels raising concerns that doses may have been diverted from plants in Belgium and Germany to the UK.

The EU wants AstraZeneca to provide doses from its two plants in Oxford and Staffordshire to make good on the production problems in Belgium, a proposal that is being resisted.

The company recently informed the commission that it would be able to deliver only 25% of the 100m doses expected in the first quarter of this year.

Clément Beaune, France’s Europe minister, said the firm could face “penalties or sanctions” if found to have given priority to British orders of the vaccine.

He said: “These are serious accusations, so it is not done lightly. I am not saying that there is a problem but if there is a problem and that we have favoured other destinations, other countries – for example the UK over us – then we will defend our interests.’

“Our contracts need to be respected. Respecting contracts are not moral commitments, they are legal commitments. Penalties or sanctions can be triggered in every contract.”

The EU has a 336m contract with AstraZeneca to provide 400m doses of which a quarter was due before the end of the March. Not all of the money has been paid to the company.

Asked if the EU could hold back payment to AstraZeneca, Beaune said: “Yes, for example. Or by not ordering supplementary doses, or the penalties all which have been foreseen by the contract.

“But if it’s an industrial glitch, that results in a reduction in deliveries for Europe and not for the others, that’s a problem.

“I don’t want suspicion, [or] conspiracy, but we need clarity and transparency. At the moment, there is an investigation that is in the process of being finalised to see precisely what was delivered in Europe and to the UK from factories that produce in Europe. If there has been a preference granted to the British, then that’s a problem.”

The EU has introduced an export authorisation scheme to force vaccine suppliers to seek agreement on any doses leaving the bloc. It has also demanded disclosure of the last three months of exports.

Last week AstraZeneca’s chief executive, Pascal Soriot, had said he was contractually obliged to provide the UK first with its 100m doses of the vaccine produced in partnership with Oxford University.

The UK government signed a contract with AstraZeneca three months before the commission.

Peter Altmaier, Germany’s economy minister, told the German daily newspaper Die Welt that the EU would not accept the UK being favoured over its member states.

“If it turns out that companies have not respected their obligations, we will have to decide the legal consequences,” he said. “No company can favour another country over the EU after the fact”.

The EU has suffered from a lack of supply after Pfizer also reported production problems in its plant in Belgium. The latest figures show that the UK has vaccinated 13.1% of its adult population. The EU has given a vaccine shot to 2.69% of its adult population with the roll out of first jabs suspended in Paris and Madrid, among other regions.