Ursula von der Leyen has promised Boris Johnson that future EU controls on vaccines will not disrupt contracted supplies of the Belgian-made BioNTech/Pfizer vaccine to Britain.

The European Commission president, made the commitment to the prime minister in a tense Friday night call, which followed the Commission’s controversial plan — hastily abandoned — to impose emergency border controls on vaccines entering Northern Ireland from the EU.

Ms von der Leyen tweeted that the talks with Mr Johnson had been “constructive”, adding: “We agreed on the principle that there should not be restrictions on the export of vaccines by companies where they are fulfilling contractual responsibilities.”

Mr Johnson’s allies confirmed that this included the 40m doses that Pfizer is contracted to supply Britain from a plant in Belgium. The Commission did not immediately respond to a request for comment.

The dropping of the implied threat to Pfizer exports and the abandonment of the proposal to include Northern Ireland in new export controls has calmed tension between London and Brussels.

Mr Johnson has tried this week to avoid stoking tension and inflaming a vaccine war which he believes would harm both sides and hinder the global fight against Covid-19.

“The call was fine, hopefully that’s the end of it,” said one ally of the prime minister. “We don’t plan to dwell on it.”

But Arlene Foster, Northern Ireland’s first minister, on Saturday called on Mr Johnson to follow Brussels’ lead and override part of the Brexit agreement to ease the flow of goods between GB and NI.

Article 16 of the Northern Ireland protocol has a “safeguard” clause to override the agreement, which is intended to maintain an open border on the island of Ireland. It includes checks on GB/NI trade.

The European Commission said it would invoke Article 16 to justify its initial plan to impose vaccine export controls on Northern Ireland, even though the region remains part of the EU’s single market for goods.

It cited the risk of “serious societal difficulties” in the EU if the bloc was unable to deploy enough vaccines to its own citizens.

Julian Smith, former Northern Ireland secretary, said the EU had “pulled the emergency cord” without following the proper processes that had been agreed over years of negotiations.

He told BBC Radio 4’s Today programme the move came “without anywhere near the level of understanding of the Good Friday Agreement, of the sensitivities of the situation in Northern Ireland”.

“It was an almost Trumpian act — I’m very pleased that they’ve changed their minds,” he said.

The Commission has since republished its vaccine shipment control measures with the Article 16 proposals stripped out.

The export restrictions have drawn criticism from business groups including the International Chamber of Commerce, which has warned they could lead to retaliation from other countries and have a devastating impact on global vaccine supplies.

It has also emerged that Belgium, a key location for vaccine production in the EU, has notified the Commission of a draft health law that would give it new powers to curb medicines exports.

The proposed legislation would allow Belgian authorities to restrict or ban the shipment of critical medicinal products and active ingredients, in case of shortages or potential shortages.

The Belgian government did not immediately respond to a request for comment on its application.