The integration of health and social care requires "serious political leadership", the head of the spending watchdog has said.
Sir Amyas Morse, head of the National Audit Office (NAO), urged "further and faster progress" to build a service which meets the needs of patients, an ageing population and offers value to the taxpayer.
Short-term funding arrangements and structural and cultural boundaries between the NHS and local government are among the issues which must be addressed to facilitate joint working, a report by the body said.
It comes after Prime Minister Theresa May announced a boost in funding for the NHS, which is marking its 70th anniversary.
Sir Amyas (pictured) said: "No-one across government or the civil service would disagree that health and social care have to be in balance to give people quality of life, and to use the available national and local resources as efficiently as possible.
"The hard part is agreeing how that balance is to be achieved and maintained, and who is willing to sacrifice what to bring it about.
"The NHS did not like funds being siphoned off through the better care fund, whilst local government has reservations about sacrificing over half of its financial resources towards NHS England's priorities, which risks eroding local democracy.
"The answer may life in local flexibility, but that could leave serious gaps in delivering what is needed: an integrated service.
"Serious political leadership is needed."
Financial pressures on the NHS and local government has made a close working relationship difficult, while short-term funding arrangements prevent effective planning, the report said.
It warned additional funding for health and social care "has at times been used to address the immediate need to reduce service and financial pressures in the acute sector", rather than invest in technology or implement change.
There is also a lack of understanding of the respective decision-making processes in the NHS and local authorities, the report added.
Sir Amyas said: "I can imagine that the points we make may be taken by some as discouraging, but they are made now because if they are not thought through in advance, it is likely that we will still be agreeing violently on the need for integrated care, and wondering why it has not progressed further and faster, in another few years' time."
Meg Hillier, chair of Public Accounts committee, said: "Health and social care is at a vital crossroads. But with the two sectors operating under separate regimes, achieving true integration will be no mean feat.
"With the promised extra funding for the NHS from next April, we need to be clear if this will be matched for social care.
"When discussing the money, the Government has got to start putting the patient at the centre of its thinking."
Copyright (c) Press Association Ltd. 2018, All Rights Reserved. Picture (c) National Audit Office.