Cabinet minister Dominic Raab has refused to guarantee that all people who have received a first dose of coronavirus vaccine will get a second jab within 12 weeks.
The foreign secretary was repeatedly pressed in an interview on Sky News to give a firm guarantee that supplies of the vaccines would be sufficient to deliver the second injection within the target time.
But he declined to do so, instead saying: “We absolutely are aiming for that We should be able to deliver it… We’re quietly confident".
It was initially planned to give the two doses of the Pfizer and AstraZeneca vaccines within three weeks, but the government introduced a longer delay in response to last month’s spike in infections following the emergence of a virulent new strain of Covid-19 in the UK.
Holding back the second jab for three months was intended to double the number of vulnerable over-70s, care home residents, health and care workers and people with serious health issues who could be protected by the mid-February deadline.
But it has raised concerns over the effectiveness of a single jab, with TV presenter Joan Bakewell launching legal action accusing the government of breaching the terms of approval of the Pfizer vaccine.
Asked by Sky’s Sophy Ridge whether he could guarantee that there was enough supply for all those who have had a first dose to receive the second within 12 weeks, Mr Raab said: "I think if we follow the roadmap and the supply chains that we have set out, along with the back-up that we've got because we've got the volume of doses - 360 million - and we've also got seven suppliers, we ought to be able to deliver on that.
“But of course right the way through this pandemic we've had to adapt to all sorts of different things. So we are just focused on making sure we deliver on the roadmap that we've got.
“We've got the distribution and logistics in place. The NHS, backed up by the armed forces have done an incredible job, local authorities have done an incredible job. Now we have just got to deliver on that.
“We absolutely are aiming for that. We should be able to deliver it. And actually if you look at our track record, which is what I think people should judge us on, we're well ahead of any other country in Europe, we're a global leader frankly in rolling out a responsible vaccine. And I think we are quietly confident.”