DUBLIN: Irish Prime Minister Micheal Martin said Monday that an EU move to ban vaccine exports outside the bloc would be "a very retrograde step".

"I'm very much against it," he told Irish state broadcaster RTE. "It's absolutely vital that we keep supply chains open."

EU chief Ursula von der Leyen threatened Saturday to enact a ban on AstraZeneca jab exports outside the bloc unless the firm supplies more of the 90 million doses it agreed to deliver in the first quarter of 2021.

EU leaders are due to hold a virtual summit on Thursday and Friday to discuss the faltering supply of jabs inside the bloc.

But Martin warned against any vaccine embargo.

"[If] you start putting up barriers, other countries may follow suit in terms of some of those vital raw materials that are required," he said.

"If we start that we are in trouble."

A row over export flows of AstraZeneca jabs has emerged between the EU and the UK -- which left the bloc last year following the 2016 Brexit referendum.

Britain's vaccination rollout has been hailed a success whilst EU states have lagged behind, blaming Anglo-Swedish firm AstraZeneca for failing to deliver to schedule.

The current furore is focussed on a Netherlands factory that is still awaiting official approval, but where both sides are claiming the future supply of the AstraZeneca jab and of key ingredients, EU and UK sources said.

Martin said there is "huge tension there between AstraZeneca and the European Union".

"They have not fulfilled their contracts, but there is no point in undermining the other companies" producing vaccines such as Moderna and Johnson & Johnson, he said.

He also said AstraZeneca jabs produced in the EU have been sent to Britain and that needs to be "reciprocated to some degree".