Four ridings were up for grabs in Monday's federal byelections — one each in British Columbia and Nova Scotia and two in Quebec. (Sean Kilpatrick/Canadian Press)

The Conservatives scored two federal byelection wins Monday, upsetting the Bloc Québécois in eastern Quebec and cruising to an easy victory in Nova Scotia.

The Bloc easily retained the riding of Hochelaga in Montreal's east end, while the New Democrats had no trouble holding on to a seat in British Columbia.

Conservative Bernard Généreux, the former mayor of La Pocatière, scored an upset in Montmagny-L'Islet-Kamouraska-Rivière du loup in eastern Quebec, taking more than 42 per cent of the vote, ahead of the Bloc's Nancy Gagnon, with just under 38 per cent.

Liberal Marcel Catellier ran a distant third with 13 per cent of the vote, followed by the NDP's François Lapointe with about five per cent.

In Nova Scotia, Conservative candidate Scott Armstrong reclaimed the riding of Cumberland-Colchester-Musquodoboit Valley, a longtime Tory stronghold.

Former Conservative MP Bill Casey captured the riding as an independent in 2008 after being booted out of the Tory caucus in 2007 for publicly criticizing the budget.

Armstrong won almost 46 per cent of the vote. His nearest rival, NDP candidate Mark Austin, took nearly 26 per cent, followed by Liberal Jim Burrows at just over 21 per cent.

In the second Quebec byelection, the Bloc's Daniel Paillé romped to victory in Hochelaga with more than 51 per cent of the vote. NDP candidate Jean-Claude Rocheleau, on whom the party had pinned strong hopes, ended up with about 20 per cent.

Liberal Robert David was third with14 per cent, followed by Conservative Stéphanie Cloutier at 10 per cent.

In the B.C. riding of New Westminster-Coquitlam, the NDP's Fin Donnelly won easily, capturing more than 49 per cent of the vote. Conservative candidate Diana Dilworth was next, with just under 36 per cent of the vote, and Liberal Ken Beck Lee a distant third with 10 per cent. Rebecca Helps of the Green Party was last.

The riding had been held for the NDP by Dawn Black, who resigned to run for a seat in the provincial legislature.

The Tories had held the riding as recently as 2004.

With files from The Canadian Press