The city of Montreal says it will start reducing the speed limit on its streets in October. (CBC)

Drivers in Montreal will have to slow down, starting in October, as the city starts to lower speed limits.

The speed limit on residential streets will be reduced from 50 km/h to 40 km/h, while the limit on major arteries will remain at 50 km/h. The move doesn't affect provincial highways through the city.

The new rules will go into effect first in the boroughs of Pierrefonds-Roxboro; Saint-Laurent; Lachine and Rosemont-La Petite-Patrie; as well as in two sectors of the downtown Ville-Marie borough.

The city says the change will be gradually applied throughout the rest of its territory through the end of 2010.

André Lavallée, Montreal's executive committee vice-president, said the move is part of a series of efforts to improve road safety.

In 2008, he said there was a 13 per cent drop in the number of deaths on Montreal's roads.

The new regulations come after Montreal reached an agreement with Quebec's Transportation Ministry in July allowing the city to set its own speed limits.

Officials are in talks with the 15 other municipalities in the area and hope to be able to apply the new regulations across the entire island of Montreal.

The city says an awareness campaign will be launched to help advise people of the change.