Prime Minister Justin Trudeau has called a pair of byelections to fill vacant seats in Quebec and Manitoba.

Voters will go to the polls in the Elmwood—Transcona riding in Manitoba and the Montreal-area riding of LaSalle—Émard—Verdun on Sept. 16.

The Manitoba riding was held by the New Democratic Party until MP Daniel Blaikie resigned in March to go work for the office of the province's Premier, Wab Kinew.

Blaikie had held the federal seat since the 2015 election.

The Quebec riding was held by former Liberal justice minister David Lametti, who resigned in January after being excluded from Trudeau's cabinet during a shuffle the previous summer.

The byelections will mark the first test for Trudeau's Liberals since losing a June byelection in Toronto-St. Paul, a riding the Liberals had previously held for decades.