Brussels has been warned by a leading business group that its plans to give EU member states powers to block vaccine exports threatens to trigger retaliation and have a “devastating” impact on global jab supplies.

The International Chamber of Commerce said in a letter to Ursula von der Leyen, European Commission president, that the move to limit exports — which is expected as early as Friday — could “very rapidly erode essential supply chains”.

The warning came as the battle over scant supplies of Covid-19 jabs in rich countries intensifies, with Ms von der Leyen ramping up pressure on AstraZeneca, the company at the centre of controversy this week over vaccine availability.

Speaking to German radio, Ms von der Leyen said the company had not provided any “plausible explanation” for why it will not supply the agreed number of doses. The European Medicines Agency is expected to announce later on Friday whether it has approved the Oxford/AstraZeneca vaccine for use in the EU.

The ICC letter was prompted by commission plans to force companies to report all plans to export vaccines to national authorities, which would then have the power to stop shipments.

John Denton, ICC secretary-general, wrote: “Our immediate fear is that the proposed EU export controls risk triggering retaliatory actions by third countries that could very rapidly erode essential supply chains.

The letter, which is dated Thursday and has been seen by the Financial Times, went on: “Such a chain of events — which seems entirely foreseeable given the rapid escalation in trade barriers on personal protective equipment at the outset of the pandemic — would have devastating implications on the supply of vaccines globally, including across EU member states.”

Mr Denton, whose organisation represents more than 45m businesses worldwide, said the EU move — while “ultimately well-intentioned” — could also hurt poor countries that depend on manufacturing facilities in Europe for their supply. “I would encourage you to consider the potential effect of a prolonged pandemic in the developing world on the European economy,” he wrote.

The commission did not immediately respond to a request for comment on the ICC letter.

Europe’s main pharmaceutical industry association has also joined the business backlash against the Brussels proposals. The European Federation of Pharmaceutical Industries and Associations said Brussels’ plans could “undermine the supply of vaccines in Europe and around the world”.

“It is vital that any measures proposed by the Commission and the Member States do not restrict, hold back, or have other negative impacts on exports of vaccines or the import of key vaccine manufacturing supplies,” it said. “Risking retaliatory measures from other regions at this crucial moment in the fight against Covid-19 is not in anyone's best interest.”

In a widening EU effort to tighten its grip on vaccine supplies, Charles Michel, European Council president, has proposed the use of new legal powers and “enforcement measures” to ramp up jab production and address “severe difficulties” in the supply of certain products.

One EU official suggested the proposals, floated in a letter this week from Mr Michel to the leaders of four member states, could enable the bloc to require companies to share patents, licences and knowhow needed to broaden vaccine production.