Downing Street has refused to rule out sending UK-made Covid-19 vaccines to Europe before all Brits have had their jab.
The EU has demanded doses from British plants in a bitter row with pharmaceutical giant AstraZeneca over supply shortages on the continent.
Cabinet Minister Michael Gove insisted there will be “no interruption” to British vaccine supplies.
But he left the door open to aiding the EU, saying the UK will consider “how we can help” the vaccination effort on the continent.
The row began when AstraZeneca said it would cut supplies to the EU by 60% up to March due to problems with its factory in Belgium.
Brussels is pushing the pharmaceutical giant to sent supplies from its British factories, but the firm says its contracts mean these doses are earmarked for the UK.
The AstraZeneca jab, which was developed with Oxford University, has not yet been approved for use in the EU, with a decision is expected on Friday.
Mr Gove told BBC Radio 4’s Today programme that vaccine doses would not be diverted to the EU.
He said: “No, the critical thing is we must make sure that the schedule that has been agreed and on which our vaccination programme has been based and planned goes ahead.
“It is the case that the supplies that have been planned, paid for and scheduled should continue, absolutely. There will be no interruption to that.”
In another interview, he said: “Of course it is the case that we will want to talk with our friends in Europe to see how we can help, but the really important thing is making sure that our own vaccination programme proceeds precisely as planned.”
The Prime Minister’s spokesman repeatedly failed to rule out sending doses to the EU once the the most vulnerable have had their jabs during a briefing with journalists on Thursday.
Asked about Mr Gove’s comments, the spokesman said: “The CDL (Mr Gove) also said it remains our priority to vaccinate the most vulnerable people across the UK to ensure we can give those who are at clinical risk protection against the virus.”
Pushed on whether that left the door open to sending vaccines to Europe once the top priority groups have been vaccinated, he said: “Phase one includes those who are most vulnerable to the virus – that remains our priority to make sure we get vaccines to all those as quickly as possible.
“Phase one is groups one to nine (on the Joint Committee on Vaccination and Immunisation suggested priority list). The mid-February target is the first four groups within that.”
Put to him that after the first nine cohorts had been vaccinated, vaccines could then be shared, the spokesman added: “I didn’t say that.”
“I don’t want to interrupt the supply of vaccines into the United Kingdom,” he told LBC Radio.
EU health commissioner Stella Kyriakides said there have been “constructive” talks with AstraZeneca after the bloc warned the firm it is contractually obliged to send jabs produced in the UK to 27 EU member states.
AstraZeneca boss Pascal Soriot said “teething issues” with the supply chain were ironed out for the UK because Britain signed a contract three months earlier than the EU.
But Ms Kyriakides said: “We reject the logic of first come first served.
“That may work at the neighbourhood butchers but not in contracts.”