Northern Ireland's health trusts have collected over £15m from hospital car parking charges in a three-year period.
The revenue raised almost doubled from 2016/17 to 2018/19, figures show.
In some cases, people were fined and even clamped because they had not complied with parking regulations.
More than 22,000 penalties were issued for parking offences across the three years.
It has led to calls for hospital parking charges to be reviewed.
In total, £15,673,977 was raised by all five health trusts from parking charges across Northern Ireland in three years.
Over £2.8m of that income related to three trusts who charge staff to park their vehicles.
One trust – the Belfast Trust – received over £3m in car parking fees in 2018/19 alone.
Aidan Hanna from campaign group Patient Voice NI said no patient or employee should have to pay to park at a hospital to receive or provide care.
“This would be a good news story if the Northern Ireland health service ended all car parking charges at our hospitals,” he added.
SDLP health spokesperson Mark H Durkan stated that the figures were “indicative” of how finances have been handled across the health service as the trusts are being made to look for ways to raise revenue.
Alliance health spokesperson Paula Bradshaw said she was not in favour of car parking charges at hospitals.
The figures, which were obtained by the Belfast Telegraph through Freedom of Information requests, revealed:
• The Belfast Trust made the most from car parking charges (£6,349,932), followed by the South Eastern Trust (£4,863,858), the Southern Trust (£1,818,630), the Western Trust (£1,652,557) and the Northern Trust (£989,000).
• The Belfast Trust, South Eastern Trust and Southern Trust charged their staff a total of £2,813,889 for parking.
• 22,388 parking charge notices were issued in total by the South Eastern Trust, Southern Trust and Western Trust – the Belfast Trust did not issue any fines and the Northern Trust did not hold that information.
• Forty-eight people were clamped for car parking offences across the Southern Trust and the South Eastern Trust.
Hospital car parking charges are decided individually by the trusts.
In 2008 guidance was published to promote greater consistency between the five trusts, setting out key principles including free parking for cancer patients and relatives who are caring for them.
At the time Health Minister Michael McGimpsey said charging was “a means of discouraging inappropriate parking by commuters and protecting spaces for patients and hospital staff”.
However, Ms Bradshaw, a South Belfast MLA, believes that relatives visiting a loved one in hospital are providing comfort, care and practical support and they should not have to pay for parking.
“There are other potential revenue raising avenues but certainly not through those people who are providing that caring service of lifting the spirits of those in hospital,” she said.
“I am not in favour of the charges but when the health trusts are faced with such financial constraints I suppose they are trying to find ways they can bring in extra income.”
Referring to parking charges for staff, Ms Bradshaw said workers are under enough pressure due to the lack of pay parity in the health service.
“It's an extra tax on their wages,” she added. “I am just very anti-car parking charges in a healthcare setting.”
Mr Durkan called for a review of parking charges and was disappointed to see that healthcare staff paid over £2.8m in parking fees.
“Trusts have been made to look for ways to raise revenue,” continued the Foyle MLA.
“They should be allowed to be more focused on carrying out operations rather than carrying on these type of operations.
“This is one area where they can actually generate revenue but I think it's ridiculous that they have to do that.
“If you look at the money they raised, and while it sounds like a massive amount of money over three years, in the wider scheme of the health budget it's a drop in the ocean.
“A significant percentage of that money has come from staff who are not particularly well paid, with many being underpaid, and they're having to pay for parking.”
Last month the government announced that thousands more NHS patients and visitors will be able to access free hospital car parking in England.
From April, all 206 hospitals trusts in England will be expected to begin offering the concession in line with the government's manifesto promise.
People with disabilities and NHS staff working night shifts will benefit from the scheme.
NHS hospital car parking fees were abolished in Scotland and Wales in 2008, although a small number of hospitals in Scotland still charge as they remain tied in to contracts with private companies that manage their parking facilities.
Visitor car parking charges and exemptions per Trust.
Royal Victoria Hospital: £1.60 for up to four hours.
Belfast City Hospital: £1.10 for first hour.
Mater Hospital: £1 for 24 hours
Patients can park for free if receiving treatment for radiotherapy or chemotherapy, and renal dialysis. Next of kin, partners or relatives can also avail of free parking if they are transporting a patient receiving treatment for any of the above.
Antrim Area Hospital and Causeway Hospital: £1.30 for up to one hour.
Car parking charge exemptions apply for patients/relatives attending the hospital for cancer or renal treatment. Next of kin of those in ICU, seriously sick patients, neonatal patients and the parents or carers of sick children can also park for free.
South Eastern Trust
Ards Community Hospital: £1.20 for up to one hour.
Lagan Valley Hospital: £1.20 for up to one hour.
Ulster Hospital: £1.20 for up to one hour.
Patients can park for free if they are undergoing renal dialysis, cardiac rehabilitation or are attending the McDermott Unit at the Ulster Hospital.
Next of kin, partners or relatives can also avail of free parking if they are transporting a patient receiving treatment for any of the above.
Craigavon Area Hospital and Daisy Hill Hospital: £1.20 for up to one hour.
Free parking is available for patients undergoing renal dialysis and cancer treatment. Next of kin, partners or relatives are also eligible if transporting the patient.
Altnagelvin Area Hospital, South West Acute Hospital and Omagh Hospital and Primary Care Complex: £1 for up to one hour.
Patients with specific acute conditions, who are required to attend the hospital on a regular basis, shall, during their period of treatment, be entitled to free parking on site.
Free car parking will be issued to anyone who meets the eligibility criteria.