Austrian Chancellor Sebastian Kurz criticised a so-called European "bazaar" of additional vaccine doses, stating that some EU member states were getting more vaccine doses than others.
"There is said to have been a bazaar where additional contracts between member states and pharmaceutical companies are said to have existed," Kurz said.
The Austrian chancellor added that deliveries had not occurred based on population and that there were differences between member states at what national media said was a "hastily organised" press conference.
Kurz said Malta, for instance, would receive more vaccines than Bulgaria and that the Netherlands had also benefited from additional doses.
He accused some member states of signing non-disclosure agreements about vaccine contracts and called for "transparency and clarification" on vaccine contracts.
Malta's deputy prime minister Chris Fearne said in a statement provided to Euronews that the country had procured all vaccines "within the framework of the Advanced Purchase Agreements and the Joint Procurement mechanisms as agreed by the European Commission and through the EU Joint Steering Committee."
He added that the co-chair of the Steering Committee is a representative from Austria.
At the daily Commission press conference, spokesman Stefan de Keersmaecker said that the "starting point" for vaccine distribution is based on population but that member states "may decide to ask for less or more of a given vaccine and this is discussed between the member states."
"A new distribution key is agreed upon with the company following, again, agreement and discussions with all the member states," de Keersmaecker said, adding that member states place their purchase orders directly with the companies based on what was agreed with the Commission.
There has been much attention placed on the negotiation of vaccine doses amongst EU member states amid overall disappointment at what is widely viewed as a sluggish rollout compared to the United States, United Kingdom and Israel.
In an earlier interview with Euronews, Fearne said that his country had paid for the maximum amount of vaccines that it was possible to buy.
"Early on, we opted to maximise the amount of vaccine we put on order before the companies that the European Commission had been negotiating with and availing ourselves all possibility within the joint purchase agreement that we could,” Fearne told Euronews.
French President Emmanuel Macron had said that European countries were able to opt for additional doses that were not taken by other countries, echoing earlier comments from the German government.
Macron said that countries that "under-ordered" doses now were coming back to get more doses.
The French health ministry later told Euronews that the country planned to send 300,000 vaccine doses to the Czech Republic, Slovakia and Austria.
Those are doses that will then be deducted from those three countries’ vaccine stocks later on in the year, the health ministry said.
Kurz has not been shy to criticise the EU's vaccine strategy, previously stating that the European Medicines Agency was slow to approve coronavirus vaccines.
He recently travelled to Israel with Danish Prime Minister Mette Frederiksen to consider creating second-generation coronavirus vaccines in the country.