A heatwave in Quebec has killed at least 19 people in the past week as high summer temperatures scorched eastern Canada, according to health officials.

Twelve of the dead were reported in Montreal, said regional public health director Mylene Drouin.

The Tribune newspaper said five of the deaths occurred in the past 48 hours in the Eastern Townships, a rural area just east of the city.

Late last night two more deaths blamed on the heat were recorded in a Montreal suburb, Radio Canada reported.

"My thoughts are with the loved ones of those who have died in Quebec during this heat wave," Prime Minister Justin Trudeau said on Twitter.

Ms Drouin said the victims were part of "the very vulnerable population, the elderly or people suffering from chronic or mental illnesses".

Temperatures soared to 34C with a humidity that made it feel closer to 40C, the meteorological service said.

Montreal is in the grip of a heatwave which has hit countries across the world (Pic: Climate Reanalyser)

The mercury has regularly topped 30C since last Friday in southern Quebec, accompanied by stifling humidity levels.

A government heat warning is in place for the region, but meteorologists are forecasting a drop in temperatures at the end of the week.

No deaths had been reported for the same period in the neighbouring province of Ontario, which has also sizzled under extremely high temperatures.

In 2010, a heatwave killed around 100 people in the Montreal area.