The boss of the NHS in England has defended the privatisation of services as a way of helping patients get treatment but insisted that the health service would continue to do most of the work.

Simon Stevens, the chief executive of NHS England, said that “sometimes there will be a case” for a patient needing, for example, a hip operation to use a private provider paid by the NHS and stressed that patients should decide themselves who should treat them.

He was responding on BBC Radio 4’s Today programme to questions about the NHS put by its listeners, many of which involved the outsourcing of NHS clinical services.

Stevens, an ex-Labour government health adviser under Tony Blair, started in the NHS’s top job on 1 April after 10 years working for UnitedHealth, an American private health firm.

Asked if it was his intention to have more private companies delivering care, he replied: “No. Most services in this country are delivered by the NHS and that’s going to continue to be the case under any foreseeable future. But the tests we should be applying are that we think like a patient and act like a taxpayer and sometimes there will be a case for whether you need a hip operation [being done in the private sector, but paid for by the NHS].”

“Ninety-four pence out of every pound we spend in the NHS is spent on NHS providers. The vast majority continues to be delivered by NHS providers,” he added.

Pressed as to whether private firms would have an increasing role, Stevens again stressed that patient choice meant private involvement would continue. “I think that the vast majority of care that’s provided for NHS patients will continue to be provided by NHS providers, but ultimately it’s patients that should make that choice, not someone sitting in an NHS office.

“The vast majority of NHS-funded care will continue to be delivered by NHS hospitals, NHS staff and NHS community services,” he added.

Recent Department of Health figures showed that non-NHS providers of healthcare, including private firms, received more than £10bn of the NHS’s almost £100bn budget last year.

Stevens also defended the NHS’s use of the private finance initiative, pioneered by the last Labour government in which he was a health policy adviser, despite concern that it is adding to some hospital trusts’ money problems and has saddled the NHS with billions of pounds of repayment costs for years to come through expensive long-term contracts. The scheme had given the NHS important new and modernised hospitals, he said.

But he backed the idea of other hospitals following the example set recently by Northumbria Healthcare foundation trust in buying itself out of its PFI contract. In the first deal of its kind it borrowed £114m from its local council to pay up and end the contract with the firms that build Hexham general hospital in Northumberland. The move is expected to save the trust an estimated £3.5m a year for the next 19 years.

Asked if other hospitals should do the same, as some are considering, Stevens said: “Where that makes sense we should clearly do it.”

Stevens failed to offer any view on TTIP, the trade deal between Europe and the US being negotiated, despite the fears that it would force NHS services to be opened up to competition and permanently entrench privatisation in the service.

Defending NHS England’s plan, in its new NHS Five Year Forward View blueprint for how the service should change during the next parliament, that improved efficiency and productivity could help produce £22bn of savings to help close the £30bn gap in its finances it expects to have developed, without radical action, by 2020/21. But he ruled out further pay freezes for the NHS’s 1.3 million staff contributing to that. Continuation of that policy, which has seen NHS pay frozen or pegged to just 1% annual increases under the coalition, would make recruitment harder at a time when staffing is an issue, he said.

The NHS England boss also appeared to defend his organisation paying GPs £55-a-time for diagnosing patients who have dementia, a move that critics have claimed is “putting a bounty” on certain patients and is unethical because, for the first time, it offers doctors financial incentives to diagnose a specific condition.

Only just over half of the estimated 700,000 people in England believed to have the disease have so far been diagnosed, and the NHS wants to increase that to two-thirds so that patients could then access and social support to help them, he said.

The payments scheme was supported by the Alzheimer’s Society and other organisations, Stevens said.

Some GPs have called for family doctors to boycott the payments. Professor Sir Simon Wessely, the president of the Royal College of Psychiatrists, dismissed the scheme. Money for dementia should be spent on improving social care for those with the condition or on research which may yield new treatments that slow its progress. “Until that happens I can see little point in this initiative,” Wessely added.