Canada is concerned about the overall integrity of the system that educates hundreds of thousands of international students and not just the added pressure they put on housing, Immigration Minister Marc Miller said in an interview with the Canadian Broadcasting Corporation.

Canada is on track to bring in 900,000 international students this year, Miller said in the interview aired late on Saturday, which was more than at any point in history and roughly triple the number who entered the country a decade ago.

The university ecosystem that brings in foreign students “is very lucrative and it’s come with some perverse effects, some fraud in the system. Some people taking advantage of what is seen to be a backdoor entry into Canada,” Miller said.

Private and public universities generate C$20-C$30 billion ($14.7-$22.1 billion) per year in revenue from those who come to study from abroad, Miller said. Canada is a popular destination for international students since it is relatively easy to obtain a work permit.

“Some people are making a lot of money out of it legitimately, some people are gaming the system, and my principal concern is with that integrity of the system,” he said.

Miller said his concern was not the public universities, but “principally the private colleges that have just ballooned in different parts of Canada”.

The opposition Conservative Party has repeatedly attacked Liberal Prime Minister Justin Trudeau’s government for failing to solve the housing squeeze.

The housing minister recently said the government is mulling whether to cap the number of students allowed each year as a way of easing the housing crunch, but Miller was sceptical.

“Just putting a hard cap, which got a lot of public play over the last few days, is not the only solution to this,” Miller said.