The UCP government's decision to freeze funding for new supervised injection sites in Alberta increases the risk of people dying of an overdose, say advocates on the front line of the opioid crisis.

"It's very distressing because we know that these sites save lives," said Petra Schulz, an Edmonton mother who lost her son to a fatal overdose in 2014.

She is the founder of Moms Stop the Harm, a group that advocates for a harm-reduction approach to fighting addiction.

It's imperative the UCP government continue to fund the efforts currently in place, she said.

"We are just hoping that this investment will be in measures that are evidence-based, measures that save lives."

Alberta's associate minister of Mental Health and Addictions, Jason Luan, announced Friday that funding for all new supervised-injection sites will be frozen until the UCP government conducts a review of the sites.

Sites planned for Medicine Hat and Red Deer, as well as a mobile site in Calgary are now on hold.

The review will look at the effectiveness of the sites, as well as the socio-economic impact on the community around them.

"We need a balance in our review," said Luan on Monday.

"In order to spend the money very wisely and responsibly, we do need to take a look at what have we learned from our current success."

There is no timeline for the review, but Luan hoped to have more information by the end of the week.

"This is a top priority," he said.

More than 2,000 overdoses were reversed in 2018 at the supervised injection sites located in Edmonton, Calgary and Lethbridge, according to data from Alberta Health Services.

Kym Porter, a Medicine Hat mother who lost her son to an overdose three years ago, said her community desperately needs a supervised consumption site to reduce overdoses.

"They save lives," Porter said. "They connect vulnerable people to supports in the community."

She's launched a petition to ask the UCP government to lift the funding freeze.

"We wanted to make Mr. Kenny aware that we think he's making an ethically and morally wrong decision, and we hope that he will reverse that decision," Porter said.

The review launched by the UCP government is unnecessary, said NDP Mental Health and Addiction critic Heather Sweet.

There is no evidence that the sites increase crime in the neighbourhoods where they are located, she said.

"We know for a fact, even just recently in Red Deer, that the RCMP came out and said that actually crime has decreased around these sites," Sweet said. "Part of that is the fact that there are supports in place to address those issues."

The advocacy group Friends of Medicare called on Albertans to write letters in support of supervised injection sites to Luan, as well as Health Minister Tyler Shandro.

The sites are subjected to a rigorous approval process, which includes community consultations, said executive director Sandra Azocar.

"I don't know what else they're going to be looking for when it comes to something that has already undergone extreme consultation," Azocar said.

Investing in supervised injection sites will also reduce health care costs down the road as addicts who lack supports are often hospitalized, she said.

"The health-care system increases exponentially when we have people that are unhealthy within our society," she said.

"We need to invest so that we can actually get people back into mainstream society."