The health secretary has criticised Apple over the roll-out of the government's coronavirus app, accusing it of "intransigence".
Matt Hancock told Sky News the tech firm would not make a change required to make the COVID-19 contact-tracing app work.
Sky News has contacted the company for comment.Hancock on virus app: 'We backed both horses'
In a major U-turn, the government confirmed earlier this week that it was abandoning efforts to develop its own coronavirus contact-tracing app in order to focus on technology from Apple and Google.
Speaking to Sophy Ridge On Sunday about the change in tack, Mr Hancock said: "There were clearly problems with ours because it worked on Android, and Apple wouldn't make the change to allow it to work on Apple.
"Of course I wish we had brought it in sooner, I wish that Apple had made the change for it to work in Apple phones in the same way that the original works on Android phones, but we will get there."
He added: "The moment that Apple and Google brought forward their technology we started working on that as well.
"So absolutely it's perfectly a reasonable point that people make that Apple have in the past also been intransigent in the face of perfectly reasonable requests from democratically elected governments to work with them on solving particular problems, whether that's about solutions to terrorism or other technical problems.
"And so absolutely I understand that reluctance on their part and to be fair to Apple they may have good technical reasons for it which are under the skin of things."
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Addressing the U-turn at Thursday's coronavirus news conference in Downing Street, the health secretary defended the move.
Mr Hancock said that joining forces with Apple and Google would offer a new, improved design.
He added that some of the features of the now-abandoned NHSX app will be incorporated into a new design with the two tech firms.
Mr Hancock said developers had been working on both the NHSX app and the design offered by Apple and Google since May, but a "technical barrier" was encountered when testing the NHSX app on the Isle of Wight.
"We found that our app works well on Android devices but Apple software prevents iPhones being used effectively for contact tracing unless you are using Apple's own technology," the health secretary said.
He said the NHSX app was better at measuring distance than the Google-Apple model.
"As it stands, our app won't work because Apple won't change their system, but it can measure distance," Mr Hancock explained.
"And their app can't measure distance well enough to a standard that we are satisfied with."
He said the best way forward was to work together to overcome the issues, adding: "We have agreed to join forces with Google and Apple to bring the best bits of both systems together.
"We will share our algorithm and the work that we have done on distance calculation and combine that with their work to deliver a new solution."
Mr Hancock told Sky News he was "highly confident" the app will see the light of day.
But he added: "Given my experience over the last three or four months on this one, I'm not going to put a date on it, we'll just work incredibly hard to make it happen."