The UK is running out of care home places and soon there will not be enough to look after the growing number of vulnerable older people needing specialist care, the president of the British Geriatrics Society has warned.

Prof Tahir Masud, fears that because so many care homes have collapsed in the past few years that the quality of those left will also decline as a result.

More than 100 care home operators collapsed in 2018, taking the total over five years to more than 400 and sparking warnings that patients in homes that close down could be left with nowhere to go but hospitals.

“I’m concerned that we will not be left with enough care homes,” said Masud. “Then where are all these vulnerable, older people going to go? At the moment, [the system is] just about hanging in and it’ll probably be OK for a year or two, but after that, the wheels could come off completely. Slowly, things are going to wind down. Quality will go down.”

Three out of five MPs say people in their constituencies are suffering because of cuts to social care, with three-quarters saying there is a crisis in care in England, according to a recent poll by the NHS Confederation, which leads Health for Care, a coalition of 15 organisations.

The number of people in the UK aged 85 or over is expected to more than double in the next 25 years. By 2040, nearly one in seven Britons will be over 75.

But the cost of care is rising far more quickly than the amount of money that local authorities pay for it, which in some cases is being cut and in many others not rising at all. Research from the Association of Directors of Adult Social Services has shown that councils had £700m of social care cuts planned in 2018-19, despite growing demand.

Already facing crippling debts from before the financial crisis, UK care home firms are collapsing under the pressures. Major operators to suffer financial difficulty include Four Seasons Health Care, which has been put up for sale after rescue talks failed, seven years on from the high-profile collapse of Southern Cross.

Martin Green, the chief executive of the social care trade body Care England, has called for for the government to put more money into social care to avoid a shortage of beds in a sector that provides care and accommodation for more than 410,000 residents.

The future of funding for the sector is due to be laid out this year in a much-delayed government green paper intended to address a £3.5bn shortfall expected by 2025.

“The worry is that many homes will close,” said Masud, a consultant physician at Nottingham university hospitals NHS trust and an honorary professor at the University of Nottingham. “If it’s the cheaper ones that close, then only those who can afford the expensive ones will be able to find a place and what will happen to everyone else?

“If, however, it’s the more expensive homes that close because people can’t afford it and only the cheap ones are left, then those homes won’t be able to provide quality of care with the money they’re charging.”

Masud blamed the uncertainty caused by the delays to the green paper. “Until we get the green paper, funding is just so uncertain. We desperately need the government to get its act together. We need this green paper and we need to have a proper debate that the public should have a say in about how we fund social care going forward,” he said.

Masud said that decisions made over employment in a post-Brexit Britain were key to whether the care home system survived. Pointing out that few, if any, care home workers earned above the necessary £30,000 immigrant salary threshold, he said: “If care homes can’t afford to bring in good people from outside the UK prepared to work for lower wages and as few people inside the UK want to take the jobs instead, as is the case now, then care homes will be forced to employ people they might have concerns about. The risk then is of abuse and very low quality of care.

Masud said many care homes were good, but he added: “If I was poor, I would be very concerned now about the quality of care my loved one would receive if they went into the only homes I could afford.

“If I had some assets, I would be less concerned about quality but I would be concerned about my inheritance.”

Masud also said he was angry about the lack of government planning for the substantial increase in older people who will need the NHS in the near future.

“The number of those aged over 85 is going to rise exponentially in the coming years and politicians have not understood that,” he said. “The consequence is demand of frail older people in our hospitals is going to go up very significantly, and if you don’t plan, there’s going to be trouble in terms of resources and of staff.

“As a country, we just don’t plan for 10 years ahead,” he added. “It potentially could lead to serious issues around quality of care we can provide for older people.”

Masud said the lack of geriatrics doctors was a key concern. “To prevent older people going into hospital, we need more geriatric doctors to go out into the community,” he said. “But there are already barely enough of them in the areas they’re also acutely needed: in the hospitals. We’re just not training enough.”

A Department of Health and Social Care spokesperson said: “We have given local authorities access to up to £3.9bn more dedicated funding for adult social care this year, and a further £410m is available for adults and children’s services.”