The prime minister conceded the government had not made enough progress during an interview with TalkTV.
Rishi Sunak has admitted the government has failed on a pledge to cut NHS waiting lists in England.
The prime minister said the government has “not made enough progress” but that industrial action in the health service “has had an impact”.
Mr Sunak made the comments in a TalkTV interview with Piers Morgan.
Cutting NHS waiting lists is one of five priorities Mr Sunak set out in January 2023, along with measures on the economy and illegal immigration.
At the time he said “NHS waiting lists will fall and people will get the care they need more quickly” but did not set a timeframe for achieving that.
Asked by Mr Morgan if his government has failed to achieve that pledge, Mr Sunak said: “Yes, we have.”
The prime minister continued: “What I would say to people is that we’ve invested record amounts in the NHS – more doctors, more nurses, more scanners.
“All these things mean the NHS is doing more than it ever has but industrial action has had an impact.”
Strikes by nurses and some other health workers ended last summer, following a pay deal with the government.
However, a dispute with junior doctors and consultants is ongoing, with walkouts continuing.
The comments come a month after Mr Sunak told the BBC’s Sunday with Laura Kuenssberg he expected to see measures designed to reduce waiting times to start taking effect in spring 2024.
As of November 2023, the overall number of waits for non-emergency care in England stood at around 7.6 million.
While there was a slight decrease on the number of waits compared with the previous month, that figure is roughly 400,000 higher than at the start of 2023.
The prime minister’s full hour-long interview with Mr Morgan is due to be aired later on Monday.