The EU has reversed its decision to temporarily override part of the Brexit deal amid an ongoing row over Covid vaccine supplies in the bloc.
The move could have seen checks at the border of Ireland and Northern Ireland to prevent shipments entering the UK.
The Brussels' U-turn came hours after announcing it, following condemnation from London, Dublin and Belfast.
However, the EU said it had "no choice" but to press on with introducing export controls on vaccines.
The EU insists its controls are a temporary scheme, not an export ban. But the World Health Organization is among those criticising the move, saying it could have a knock-on effect around the world.
The Brexit deal guarantees an open border between the EU and Northern Ireland, with no controls on exported products.
However, Article 16 of the Northern Ireland Protocol part of the deal allows the EU and UK to choose to suspend any aspects they consider are causing "economic, societal or environmental difficulties".
Earlier on Friday evening the EU announced it would trigger the clause and introduce the export controls on its vaccines entering Northern Ireland in a bid to prevent the region becoming a backdoor for jabs to be sent to the UK mainland.
It said the actions were "justified" to avert problems caused by a lack of supply.
But the proposals sparked concern from all five parties in Northern Ireland's devolved government and Irish prime minister Micheál Martin.
But later on Friday evening, following talks with UK Prime Minister Boris Johnson, European Commission President Ursula von der Leyen tweeted that the UK and EU had "agreed on the principle that there should not be restrictions on the export of vaccines by companies where they are fulfilling contractual responsibilities".
She said the backtrack, which was outlined in a European Commission statement, came after "constructive talks" with Mr Johnson in which he had expressed "grave concerns" about the initial plan.
The BBC's Brussels correspondent Kevin Connelly said Ms von der Leyen's midnight tweet seemed to "wind down" the idea that there could be a "vaccine war" where jab supplies are prevented from reaching the UK.
BDST: 1530 HRS, JAN 30, 2021