Liz Truss has said it is "too early" to determine when the UK will send coronavirus vaccines abroad, as she guaranteed there will be no disruption to jabs coming from the European Union.
The International Trade Secretary said that "we first need to make sure that our population is vaccinated" but insisted it would be damaging to become a "vaccinated island" while other countries go without.
Ministers have agreed to a "reset" in relations with the EU after Brussels imposed export controls on vaccines, as the bloc suffers supply shortages from pharmaceutical giant AstraZeneca.
Brussels backtracked on a widely condemned move to override part of the Brexit agreement on Northern Ireland to control shipments of jabs, risking a hard border with the Republic.
Asked if she could guarantee that the supply of Belgium-made Pfizer jabs would not be disrupted, Ms Truss told The Andrew Marr Show on the BBC: "Yes I can.
"The Prime Minister has spoken to the president of the European Commission. She has assured him that there will be no disruption of contracts that we have with any producer in the EU."
But with predictions that the UK will ultimately have a surplus of jabs after vaccinating the population, questions have turned to when the Government will help other nations.
"Of course, we first need to make sure that our population is vaccinated. We have a target to get the most vulnerable vaccinated by mid-February," Ms Truss told Sky's Sophy Ridge On Sunday.
"It's a bit too early to say about how we would deploy 'XX' vaccine, but we certainly want to work with friends and neighbours, we want to work with developing countries because we're only going to solve this issue once everybody in the world is vaccinated."
She was pressed whether the UK would aid allies and developing nations before autumn, when the Government aims to have offered jabs to the entire population.
"There have been supply issues so we need to make sure the new drugs that are coming online are delivered, the population is vaccinated," Ms Truss responded.
"But as we're developing that, we're also working with other countries about how we can help because it won't benefit people in Britain if we become a vaccinated island and many other countries don't have the vaccine, because the virus will continue to spread."
Ms Truss was forced to defend the Government's policy on borders, which critics say has been lax with protections consistently coming too late.
She told Ridge "we have been very tough on the borders" but said "you cannot hermetically seal the UK borders" because of the economy.
The Cabinet minister declined to rule out that some social distancing measures will be in place for the rest of the year after research from scientists advising the Government suggested deaths are only substantially reduced alongside a gradual relaxation of restrictions if vaccines have infection efficacies of 85%.
"I don't want to make predictions about the situation in the autumn, I think it's far too far away," Ms Truss said.
Cabinet Office Minister Michael Gove said on Saturday that the EU recognises it "made a mistake" in its short-lived but widely condemned move to trigger Article 16 of the Northern Ireland Protocol to control shipments of jabs.
A compromise was struck to prevent a possible hard border with the Republic of Ireland after a flurry of diplomacy followed the EU's surprise move on Friday.
Foreign Secretary Dominic Raab said he was "reassured the EU has no desire to block suppliers fulfilling contracts for vaccine distribution to the UK" after talks with European Commission executive vice-president Valdis Dombrovskis.
Mr Gove also said the Government is "fully on course" to hit its target of vaccinating the 15 million most vulnerable individuals in the UK by mid-February, as official data showed 8,378,940 had received first doses.
But the increase of 487,756 first doses came as ministers announced a further 1,200 people had died within 28 days of testing positive for Covid-19 as of Saturday, bringing the official UK total to 105,571.