A European Union legal case against British-Swedish drugmaker AstraZeneca began in a Belgian court on Wednesday.

The European Union announced Monday that it is suing AstraZeneca over an alleged breach of its vaccine supply contract in a dramatic escalation of a months-long dispute over delivery delays that hampered the rollout of shots across the continent.

The 27 nations of the European Union had ordered 300 million doses of the Covid-19 vaccine from the drugmaker to be delivered by the end of June, with an option to purchase an additional 100 million. But deliveries of the vaccine repeatedly fell short, sparking a bitter public fight over the terms of the contract.

AstraZeneca said in March it was aiming to send 100 million doses in total to the union in the first half of the year — just a third of what was expected.

The Belgian court told CNN on Wednesday that the EU's legal case asks whether the company can take measures to catch up on delayed production and delivery to the bloc, as per the contract.

The court is tasked with looking at that request and whether AstraZeneca should be fined if they are unable to comply, a spokeswoman of the Belgian Court of First Instance in Brussels told CNN.

Speaking outside the court on Wednesday, lawyer Hakim Boularbah, who is representing AstraZeneca, said: “The only statement I can make is that AstraZeneca deeply regrets the decision of the European Commission to take this action to court. They hope the dispute will be resolved as soon as possible.”

A lawyer for the commission, Rafaël Jafferali, told cameras outside court that “We made our case in court. We explained the situation. Our comments are for the court.”

The next court hearing is scheduled for May 26.

The judge, who has not been named, is expected to take three to six weeks to come back with a ruling.