The European Union took on vaccine producer AstraZeneca in a Brussels court on Wednesday, with the urgent demand that the company needs to make an immediate delivery of Covid-19 shots the bloc insists were already due.

AstraZeneca's contract signed with the European Commission on behalf of member states foresaw an initial 300 million doses for distribution among all 27 countries, with an option for a further 100 million.

The doses were expected to be delivered throughout 2021. But only 30 million were sent during the first quarter.

Deliveries have increased slightly since then but, according to the European Commission, the company is set to provide only 70 million doses in the second quarter. It had promised 180 million.

EU lawyer Rafael Jafferali told the court that the company now expects to deliver the total number of doses by the end of December, but he added that "with a six-month delay, it's obviously a failure".

His main argument is that AstraZeneca should have used production sites in the bloc and the UK for EU supplies as part of a "best reasonable effort" clause in the contract.

He said that 50 million doses that should have been delivered to the EU went to third countries instead, "in violation" of their contract.

Mr Jafferali has said that the company should use all four plants listed in their contract for deliveries to the EU.

He also accused the company of misleading the European Commission by providing data lacking clarity on the delivery delays.

"The information provided by AstraZeneca did not allow us to fully understand the situation before mid-March 2021," he said.

The EU has insisted its gripes with the company are about deliveries only and has said that it has no problems with the safety or quality of the vaccine itself.

The shots have been approved by the European Medicines Agency, the EU's drug regulator.

While the EU insists AstraZeneca has breached its contractual obligations, the company says it has fully complied with the agreement, arguing that vaccines are difficult to manufacture and it made its best effort to deliver on time.

Lawyers for the company will address the court later Wednesday.

As part of an advanced purchase agreement with vaccine companies, the EU said it invested 2.7 billion euros (£2.3 billion), including 336 million (£290 million), to finance the production of AstraZeneca's serum at four factories.

The long-standing dispute drew media attention for weeks earlier this year amid a deadly surge of coronavirus infections in Europe, when delays in vaccine production and deliveries hampered the EU's vaccination campaign.

Cheaper and easier to use than rival shots from Pfizer-BioNTech, the AstraZeneca vaccine developed with Oxford University was a pillar of the EU's vaccine rollout.

But the EU's partnership with the firm quickly deteriorated amid accusations it favoured its relationship with UK authorities.

While the UK made quick progress in its vaccination campaign thanks to the AstraZeneca shots, the EU faced embarrassing complaints and criticism for its slow start.

Concerns over the pace of the rollout across the EU grew after AstraZeneca said it could not supply EU members with as many doses as originally anticipated because of production capacity limits.

The health situation has dramatically improved in Europe in recent weeks, with the number of people in hospital with Covid-19, and deaths, on a sharp downward trend as vaccination has picked up.

About 46% of the EU population have had at least one dose.

In total, the European Commission has secured more than 2.5 billion of vaccine doses with various manufacturers.

It recently sealed another major order with Pfizer and BioNTech through to 2023 for an additional 1.8 billion doses of their Covid-19 shot to share between the bloc's countries.

A second hearing will take place on Friday, with a judgment to be delivered at a date to be announced.

In addition to the emergency action, the European Commission has launched a claim on the merits of the case for damages for which a hearing has not yet been set by the court.