The EU has moved to prevent Northern Ireland from being used as a back door to funnel coronavirus vaccine from the bloc into the rest of the UK.

Stormont first minister Arlene Foster branded the EU’s triggering of article 16 of Brexit’s Northern Ireland Protocol to stop the unfettered flow of inoculations from the EU into the region an “incredible act of hostility”.

The protocol, which is part of the Brexit withdrawal deal, normally allows for free movement of goods from the EU into Northern Ireland.

Under the terms of the protocol, goods should be able to move freely between the EU and Northern Ireland as the region remains in the single market for goods and still operates under EU customs rules.

The EU has triggered article 16 of the protocol to temporarily place export controls on this movement in respect of vaccines.

The move came amid a deepening row over the allocation of the Oxford/AstraZeneca vaccine after the company announced delays to its EU operations.

The move to activate article 16 will frustrate any effort to use Northern Ireland as a back door to bring vaccines into Great Britain.

Foster said: “By triggering article 16 in this manner, the European Union has once again shown it is prepared to use Northern Ireland when it suits their interests but in the most despicable manner – over the provision of a vaccine which is designed to save lives.

“At the first opportunity, the EU has placed a hard border between Northern Ireland and the Republic of Ireland over the supply chain of the coronavirus vaccine.”

The regulation means Northern Ireland will be considered an export territory for the purposes of vaccine sent from the EU/the Republic of Ireland.

Northern Ireland’s vaccines arrive from the rest of the UK at present so those will be unaffected.

The DUP leader added: “With the European Union using article 16 in such an aggressive and most shameful way, it is now time for our government to step up.

“I will be urging the prime minister to act and use robust measures including article 16 to advance the interests of Northern Ireland and the rest of the United Kingdom.”

The DUP has previously pressed the British government to invoke the article 16 mechanism because of disruption to the movement of goods between Britain and Northern Ireland.

The Cabinet Office minister, Michael Gove, has told the EU the UK is “carefully considering” its next steps.

The Chancellor of the Duchy of Lancaster (CDL) spoke to his counterpart on the UK-EU joint committee on Friday, No 10 said.

In a statement, a spokesman said: “CDL Michael Gove just spoke to European commission vice-president Maros Sefcovic to express the UK’s concern over a lack of notification from the EU about its actions in relation to the NI protocol.

“CDL said the UK would now be carefully considering next steps.”