The cash-strapped NHS may need to find an additional £4 billion every year to care for people with long-term conditions, MPs have warned.

The Health Select Committee said that these conditions are one of the "biggest challenges" facing the health service.

There is a rising tide of patients who suffer from long-term conditions such as diabetes, high blood pressure, depression, dementia and arthritis. A t the same time the number of patients who suffer from more than one long-term condition is also rapidly increasing.

Caring for these patients currently accounts for around 70% of the NHS budget in England.

But the MPs warned that demand for services is currently exceeding funding available and the situation is only likely to "worsen".

Estimates suggest that the NHS spends around £1,000 a year treating someone with one of these health issues, someone with two conditions costs around £3,000 and a person with three will need NHS funding to the tune of around £8,000 a year.

And experts have said that the current figure of around 15 million people living with a long-term condition will rise by an additional three million over the next decade.

Dr Sarah Wollaston, who has recently become chairwoman of the powerful committee, said: "I think long-term conditions are one of the greatest challenges facing the NHS.

"In 2012 we had over 15 million people who were living with at least one long-term condition but by 2025 there will be 18 million. Already 70% of the entire health and social care budget goes towards looking after the 30% of the population suffering from these conditions.

"If you have one long-term condition, The King's Fund estimates that costs the NHS around £1,000 a year, if you have two it costs around £3,000 a year but if you have three it costs around £8,000 a year.

"What we're seeing is not only an increase in the numbers of people with long-term conditions but the number of people living with multiple conditions.

"Looking at the financial impact of that, it is estimated that compared to a baseline in 2010 the NHS is going to have to find £4 billion extra a year just to be keeping pace with that demographic change and the impact of multiple long-term conditions.

"We feel that there needs to be a much greater sense of urgency as to how we're going to deal with that, not only in financial terms but the impact on people."

In evidence presented to the committee, the Department of Health said: " Without changes to services, the costs of delivering care to people with long-term conditions will continue to increase.

" If there is failure to improve the prevention and management of care for people with long-term conditions it is estimated that by 2016 there will be an additional cost pressure on the NHS of around £4 billion p.a. (2010 baseline).

"The majority of this cost pressure comes from continued inappropriate and unplanned use of expensive acute hospital services."

And the situation could worsen in the two years following 2016.

The committee said: "Cost pressures on the health and care system deriving from management of long-term conditions and treatment of the increasing prevalence of co-morbidities is likely to add £5 billion to the annual costs of the system between 2011 and 2018."

The MPs said they support the integration of the health and social care system, but questioned the prevailing view that services to treat long-term conditions should be moved out of hospitals and into the community.

They said: " The focus on treating fewer people with long-term conditions in hospital is the wrong one: what the Government and NHS England should be addressing are the factors which drive people with long-term conditions into acute hospitals through A&E in the first place.

"Cutting acute services for long-term conditions without ensuring that primary and community care services were geared up to manage the care of people with long-term conditions would be a recipe for disaster."

The report also questioned the Government's pledge to put mental health on a par with physical health.

"What we have seen is NHS England using a tariff deflater that disproportionately takes money out of mental health budgets and we don't see how that is compatible with parity of esteem," Dr Wollaston added.

During the health reforms the responsibility for long-term conditions was transferred from the Department of Health to NHS England.

But the MPs said that this meant the cross-government strategy to combat such conditions was disbanded when the responsibility was handed over and called for clarity on cross-departmental handling of the problem.

A long-term condition is a health problem that cannot be cured but can be controlled by medication or other therapies.

Dr Martin McShane, NHS England's director for long-term conditions, said: "We have already taken steps to refocus the agenda on proactive care, especially for those most at risk and with complex care needs.

"We are already working on a number of wide-ranging initiatives including incentives for proactive care, work to support the frail and elderly and the integration of physical and mental health care.

"Local working will deliver the desired change but we do not underestimate the scale of the task and NHS England is fully committed to supporting person-centred care to enhance the quality of life for people with long term conditions."