Canada has imposed retaliatory tariffs on a range of American goods, as uncertainty continues over efforts to reach a new trade deal with the United States.

The counter-tariffs, which came into effect today, cover nearly 28 billion Canadian dollars, or about 20 billion US dollars, worth of American products.

The affected goods include steel, furniture and cotton T-shirts, with tariffs reaching as high as 50 per cent. Fresh fish and lobster were initially included but were later removed following pressure from Canada's seafood industry.

The decision highlights the challenge facing Ottawa as it seeks to respond to its largest trading partner while limiting the impact on Canadian businesses and consumers.

Officials from both countries have expressed a desire to reach an agreement, but talks have yet to resume after breaking down in late August.

Canadian Prime Minister Mark Carney says Ottawa remains committed to securing a durable trade deal that serves the interests of both countries.