The Oxford AstraZeneca doses will now stay in the EU after the first use of an export control system instituted by the bloc more than a month ago.
An unnamed EU official confirmed a report that first appeared in the Financial Times.
Authorities in Italy refused to grant a licence for the doses, manufactured there, to be exported.
Officials in Rome had told EU officials of their plan and were not opposed.
The 250,000 doses will now reportedly be distributed within the EU.
It has happened because the EU fears it will be hit with shortages of the vaccine.
The EU has been in a dispute with Anglo/Swedish company Astrazeneca because fewer doses are being delivered to the bloc than it had promised.
So far, the EU has vaccinated some 8% percent of its population compared to over 30% in the United Kingdom.
The move to block the exports came after a request from Italy, which has been taking a tough line in dealing with vaccine shortages since a new government led by Mario Draghi came into power last month.
The EU introduced an export control system after facing shortages of doses in the early stages of the vaccine campaign that started in late December.
It means that companies must respect their contractual obligations to the bloc before commercial exports can be approved.
Also today, Germany approved the Astrazeneca vaccine for use in people over 65, having previously only used it for younger adults.