The pharmaceutical company says it plans to meet with EU officials in Brussels later on Wednesday.
The latest disagreement between the two sides came after AstraZeneca rejected the EU’s accusation that the company had failed to honour its commitments for the delivery of the coronavirus vaccine.
The company says figures in its contract with the EU were targets that could not be met because of problems in rapidly expanding production capacity.
AstraZeneca said in a statement that it “understands and shares in the frustration that initial supply volumes of our vaccine delivered to the European Union will be lower than forecast”.
Chief Executive Pascal Soriot made the comments in an interview with Italian newspaper La Repubblica following days of criticism from EU leaders furious about the news that initial shipments from AstraZeneca would be lower than anticipated.
Watch: COVID-19 - EU eyes UK vaccine supply as AstraZeneca row deepens
The drugmaker said last week that it planned to cut initial deliveries in the EU to 31 million doses from 80 million due to reduced yield in the manufacturing process.
“Our contract is not a contractual commitment,” Mr Soriot said. “It’s a best effort. Basically we said we’re going to try our best, but we can’t guarantee we’re going to succeed. In fact, getting there, we are a little bit delayed.”
On Monday, the EU threatened to impose tight export controls within days on Covid-19 vaccines made in the bloc.
The EU, which has 450 million citizens and the economic and political clout of the world’s biggest trading bloc, is lagging badly behind countries such as Israel and Britain in rolling out coronavirus vaccine shots for its healthcare workers and most vulnerable people. That is despite having more than 400,000 confirmed virus deaths since the pandemic began.
The shortfall of planned deliveries of the AstraZeneca vaccine comes at the same time as a slowdown in the distribution of Pfizer-BioNTech shots, as that company upgrades production facilities at a plant in Belgium.
The Oxford/AstraZeneca vaccine is expected to get medical approval in the bloc on Friday.
Reporting by Associated Press.