MONTREAL -- The mayors of Quebec's three largest cities say they're falling behind in the construction of subsidized housing for low-income tenants -- and if that wasn't obvious before, it is now, with urgent problems like Montreal's tent city of last year.

In an unusual move, they've joined forces to ask the province to invest immediately, especially as the pandemic puts an extra strain on the pre-existing housing crisis.

Montreal has undergone a major construction boom in high-rise condos and apartments. But most remain out of reach for the city's poorest.

Social housing is designed for those who earn less, allowing tenants to pay no more than 25 per cent of their income in rent, with the balance subsidized by the government.

The events of the last 12 months have created a new sense of urgency around the need for that kind of model, argue housing activists.

“Now, with the pandemic, we think the situation will be worse, because last year not only there was a pandemic, there was rent increases, really fast rent increases, in Montreal and other cities,” says Veronique Laflamme, an activist with the housing group FRAPRU.

Three of the province's mayors appear to agree: the leaders of Montreal, Quebec City and Gatineau have combined efforts to urge the province's minister of municipal affairs and housing to earmark at least $260 million to build subsidized apartments.

They say this will just allow their cities to catch up with existing demand.

In Montreal, last year's improvised tent city on Notre-Dame St. starkly highlighted the need, and just how many people are newly homeless, said Mayor Valerie Plante.

“Our people on the street are coming to us, saying 'I cannot afford my apartment anymore,' the prices are getting higher and higher, and we're seeing the distress in our population,” she said.

She said Montreal's immediate need is for 6,000 additional units.

In Gatineau, the vacancy rate there of just 1.6 per cent puts it in serious trouble as well, especially after a string of natural disasters affected areas that are usually home to many low-income families.

“We've been through tough catastrophes in Gatineau -- we've had floodings twice, we had [a] tornado," says Gatineau Mayor Maxime Pednaud-Jobin.

"Between the two floodings and now the COVID... those catastrophes have destroyed easily accessible housing units."

In Quebec City, mayor Regis Labeaume says his administration had to put a moratorium on condo conversions as four out of its six districts saw vacancy rates dip below the critical 3 per cent needed for a balanced market.

“There is a crisis in Quebec City which is quite amazing,” said Labeaume.

He says that city will need at least 2,000 subsidized units to satisfy the demand.

A spokesperson for housing minister Andrée Laforest says the current crisis is the result of the previous government's inaction on social housing.

The mayors don't deny that, but they say it doesn't change much for them. In their joint push, they're arguing it's time for the current government to reinvest massively to make up for declining public investments.