Northern Ireland's health service is paying millions of euros to a private hospital in Mullingar to treat thousands of public patients a year to shorten its waiting lists.
At the same time that the HSE is sending patients north for treatment, it has emerged that more than 1,200 people from the six counties were referred to the Republic.
The 200-bed St Francis Hospital in Co Westmeath is understood to have made around €1m from National Health Service (NHS) patients already this year.
Hysterectomies, gallbladder removal and plastic surgery are among the operations that have been carried out on patients who are transported by private bus in a 240-mile round-trip from Belfast.
The NHS has had contracts with private Dublin clinics for many years, but the contract with the Mullingar hospital is being widely seen in the North as further proof of the NHS reliance on the private sector.
The Belfast Health and Social Care Trust has spent more than €1.1m on almost 750 procedures since December.
The owner of the hospital, Mark Gordon, is originally from Belfast and bought the facility in 2010.
He said that hospital had a "very low" complication rate and feedback from northern patients was positive.
"We have been been receiving patients since January as part of the Northern Ireland waiting list initiative and have received very high patient satisfaction feedback rates," Mr Gordon said.
He added that the hospital provides a high quality service and its customers also include a large number of people from the Republic.
The figures come just days after the Herald revealed a massive increase in the number of people here applying to have their medical treatment carried out abroad.
Figures released for 2012 and the first two months of this year show almost 1,000 patients applied to travel abroad for operations.
The State spent more than €7m on 858 patients travelling abroad for operations last year.
In the first two months of this year, some 126 applications have been made for treatment abroad, of which 116 have been approved.
This is a big increase on 2011, when 481 applications were made. Some 388 were approved and 48 were declined.
The HSE operates the 'treatment abroad' scheme, which allows patients access to procedures not available here.
It allows patients to travel to another EU member state, or Switzerland, provided certain criteria are met. A referring consultant has to certify that he recommends that the patient is treated abroad, and that it is medically necessary.
Under the scheme, the HSE has to give a decision prior to the patient travelling abroad.