TORONTO -- The treatment of so-called medical tourists at a few hospitals in Ontario generates millions of dollars of revenue for the health system and benefits patients in this province, the health minister said Wednesday.

No public money can be used to care for those international patients and any revenue generated -- about $13 million per year -- must be reinvested to benefit Ontario patients, for example to open new hospital beds or hire nurses, Eric Hoskins said.

"There are clear economic benefits...but my job is to ensure that Ontarians come first, that there is no queue jumping, that it has no impact on wait times, that staff that are funded through our public system are not spending their time on international patients," he said.

The Registered Nurses' Association of Ontario, along with several other health-care organizations, urged Hoskins to ban medical tourism, aside from humanitarian cases, saying the practice promotes queue jumping.

"Canadians, Ontarians, did not make a deal with government of funding the health-care system through their taxes to treat people from abroad that simply get ahead of the line because they have money," Doris Grinspun, the CEO of the nurses' group, said at a news conference.

"It took a long time in this country to build a health system that is universal for all based on need, not on the size of our wallets and we the health-care professionals that are sitting here representing doctors, nurses, midwives and all others are not going to stay silent and allow it to happen."

The Ministry of Health and Long-Term Care is currently reviewing the practice to ensure that Ontario patients are coming first, Hoskins said. Only a small number of hospitals in the province treat medical tourists and the proportion compared to Ontario patients is quite small. Ninety per cent of the international patients Ontario sees are through the Hospital For Sick Children and University Health Network hospitals in Toronto.

Sick Kids saw 207 international patients in 2013-14, which accounted for 1.3 per cent of its total inpatient admissions and University Health Network saw 174 such patients, accounting for 0.1 per cent of its total, according to the Ministry of Health. Ministry staff weren't immediately able to say if those numbers included humanitarian patients.

The New Democrats said medical tourism is one step toward two-tiered medicine.

"It's unacceptable," said party leader Andrea Horwath. "There's no way that people should be able to pay to get services ahead of everybody else. It should be the people that get services get services because they are the ones that are most in need. That's the way our system works."