Care home managers reported almost 13,000 concerns that vulnerable residents were experiencing financial abuse in the past four years, new figures show.
The data, collected from an FOI request to the Care Quality Commission, have prompted experts to call for a Government inquiry into the scale of the issue.
The statistics show that there were 12,968 investigations of potential financial abuse by the CQC between 2013 and June last year.
Care homes have a duty to report concerns about their residents to the regulator, which then investigates the allegation.
The data shows that the majority of alleged victims were over 65, with 85 and over the most common age group.
This is an issue which should be high up on the Government’s agenda
Ann Stanyer, lawyer
In 2016, the most recent year with complete data, 848 victims were over 85, of a total of 2,826.
Older victims are significantly more likely to be female, with 617 women and 188 men in this age group flagged as potential victims.
Experts say this is partly because women tend to live longer, meaning there are more women than men among the oldest age groups.
Divorced and separated women are also thought to be at a more significant risk of abuse.
Financial abuse involves someone persuading a vulnerable person to hand over money, pressuring them to sign over property or other assets, or using cheques, credit or debit cards without their permission.
In some cases family members who have a lasting power of attorney agreement can take advantage of it to appropriate valuable possessions or money as "gifts".
Ann Stanyer, of law firm Wedlake Bell, who made the FOI requests, said the data showed there was a "very real problem identified in the care home sector".
She added: "It is unclear from the FOI results as to where the problem lies – whether the abuse is real, whether it is based on suspicions of the care home residents, whether it is perpetrated by care home staff or care home visitors."
In 2016, of those which did specify an abuser, 503 were employed by the care home, and 458 were relatives of the victim. However, 1,310 of the 2,826 did not describe the suspected abuser.
Experts called for a Parliamentary inquiry into the issue to establish the true extent of the problem and how it can be tackled, similar to the one currently in progress in Western Australia. In October the US Congress passed a law implementing better training for investigators, prevention programmes and collection of data.
Ms Stanyer said: "This is an issue which should be high up on the Government’s agenda, like in Western Australia and the US, and a positive step in this direction would be to commission a report and appoint a minister for the elderly who can lead on and create new policies in this area.
"Practitioners have serious concerns that the increased digitisation of creation of LPAs will empower abusers without any reciprocal drive to put statutory safeguards in place."
Stephen McCarthy, England director at charity Action on Elder Abuse, said the figures were the "tip of the iceberg" and the organisation supported calls for an investigation.
He said: "It would also be good to know just how many of these alleged offences in care homes have led to criminal charges or even police investigation of the perpetrator.
"As the current furore around safeguarding at Oxfam shows us, society does not consider it acceptable for criminal actions to result in merely the loss of a job.
"There has to be the genuine deterrence that only criminal prosecutions can provide."
A Government spokesman said: "Abuse of people in care is completely unacceptable in any form and we expect all care homes to protect residents from financial exploitation.
"We have introduced tougher inspections of care services and made sure that the police, councils and the NHS are working together to help protect vulnerable adults.
“We are determined to tackle fraud and that is why the Government created the Joint Fraud Taskforce, which brings together government, the banks and law enforcement to develop a collective response to it.
"Working collaboratively in this way builds on the good work already being done to tackle complex fraud issues.”