Prime Minister Mario Draghi's spokesperson Paola Ansuini confirmed the move to CNN, adding that Italy and the European Commission had agreed on the action. This is the first time that such EU measures have been used for vaccines.

The story was first reported by the Financial Times.

In late January, a public and acrimonious fight erupted between the EU and AstraZeneca over vaccine delays, after the company advised the bloc that it would deliver tens of millions fewer doses than agreed by the end of March.

The European Commission later adopted new measures giving member states the power to restrict the export of Covid-19 vaccines outside the bloc, in certain situations. The mechanism is not supposed to affect humanitarian aid or COVAX, the global initiative aiming to distribute some 2 billion vaccines to poorer countries.

The 27-nation bloc's vaccine rollout has continued to falter, pushing some increasingly frustrated member states to turn to outside nations for assistance.

Only 5.5% of the EU population of 447 million has received a first vaccine dose, according to data from the World Health Organization (WHO).

On Thursday, Italy's Foreign Ministry explained its decision to block AstraZeneca from exporting its vaccine, citing the company's delays in supplying its vaccine to Italy and the European Union, and noting that Australia is not considered a "vulnerable" nation by the EU.

According to the ministry statement, Italy has previously authorized the company's export of "modest quantities of samples intended for scientific research activities," but flagged the shipment in question because it involved 250,700 doses.

The statement cited "the high number of vaccine doses subject to the export authorization request compared to the amount of doses provided to Italy and, more generally, to EU countries so far."

AstraZeneca has declined to comment on the Italian decision.

The European Commission "did not oppose" Italy's decision to impose an export ban on vaccines for Australia, an EU official told CNN Thursday.

The official is closely involved with trade processes inside the Commission, but is not authorized to speak on the record regarding closed door meetings or on trade documents between the Commission and European Union member states.

Under EU procedures, a company wanting to export vaccines from an EU member state must notify the member state. The member state checks criteria for export and makes a draft decision on whether to approve the export. European Commissioners then have one working day to approve, amend or reject the member state's decision. The member state must follow the Commission's decision.

The EU official told CNN that EU member states approved 174 requests for vaccine export authorizations during the period from January 30 to March 1, 2021.

"The exports concerned the following export destinations: Argentina, Australia, Bahrain, Canada, Chile, China, Colombia, Costa Rica, Dominican Republic, Ecuador, Hong Kong, Japan, Kuwait, Macau, Malaysia, Mexico, New Zealand, Oman, Panama, Peru, Philippines, Qatar, Republic of Korea, Saudi Arabia, Singapore, South Africa, the United Arab Emirates, the United Kingdom, the United States and Uruguay," the official said.