The Competition and Markets Authority (CMA) also said some homes charged large upfront fees.

The initial findings of the CMA’s care homes market study also revealed many people struggle to make decisions about care, often under stressful and time-pressured circumstances, and complaints procedures are not functioning well.

The CMA said it is not realistic for many residents to move home if they are dissatisfied with the care they are receiving so it is essential that effective systems are in place for them to be able to complain.

While many care homes offer a good service, the watchdog is concerned about the lack of information about prices on care home websites, and care homes’ contracts which mean they can ask residents to leave at short notice.

It also said the sector will not be able to attract sufficient investment for the future despite figures which suggest the number of people aged 85 and over are projected to more than double by mid-2039.

Acting chief executive, Andrea Coscelli, said: “Some of the most vulnerable people in our society use care homes, often moving to them under extremely difficult circumstances. It’s therefore essential they are able to make informed choices, understand how services will be paid for, and be confident they will be fairly treated and able to complain effectively if they have any concerns.

“We also have particular concerns that some care homes might be breaking consumer law and have opened a consumer protection case to investigate further.

“Demand for care home places is expected to surge over the next two decades. To make sure the additional capacity this requires is available, it needs to be built in good time. At present, short-term funding pressures and uncertainty mean that the sector is not attracting investment. We will be focusing on finding ways to deal with these, and other concerns identified.

The year-long CMA market study launched in December 2016.

See YourMoney.com’s guide Will I have to pay my own care home fees? for more information.