The Italian government has blocked the export of an Oxford-AstraZeneca vaccine shipment to Australia.
The decision affects 250,000 doses of the vaccine produced at an AstraZeneca facility in Italy.
Italy is the first EU country to use the bloc's new regulations allowing exports to be stopped if the company providing the vaccines has failed to meet its obligations to the EU.
Australia said losing "one shipment" would not badly affect its rollout.
But it has asked the European Commission, which reportedly backs Italy's move, to review the decision.
AstraZeneca is on track to provide only 40% of the agreed supply to member states in the first three months of the year. It has cited production problems for the shortfall.
In January, then Italian Prime Minister Giuseppe Conte described delays in vaccine supplies by both AstraZeneca and Pfizer as "unacceptable" and accused the companies of violating their contracts.
The EU has been widely criticised for the slow pace of its vaccination programme.
