The U.S. Department of Commerce says it is looking into allegations that some fabricated structural steel products from Canada, China and Mexico are sold in the U.S. at prices well below their fair value.

In addition to the so-called dumping allegations, the department says it will also investigate whether producers in the three countries are receiving unfair government subsidies in the form of tax credits, grants and loans, and export insurance.

The Commerce Department says the investigations into fabricated structural steel products were initiated based on petitions from the American Institute of Steel Construction.

The AISC alleges that Canada and Mexico are dumping some steel products into the U.S. at a discount of as much as 30 per cent, while China's dumping margin is alleged to be as much as 222 per cent.

If the investigation finds the allegations are valid, it could result in duties and tariffs of that size being put on those products from those countries.

The AISC complaint also alleges that some Canadian steel products benefit from 44 government subsidy programs. In China, they allege 26 subsidies, and 19 for Mexico.

Commerce Department data suggests the U.S. imported $658.3 million US worth of fabricated structural steel from Canada in 2017. From China, the figure is $841.7 million US, and from Mexico, $406.6 million US.

The probe comes as Canada is pushing to have the U.S. remove steel and aluminum tariffs on Canadian metal products.

Transport Minister Marc Garneau said last week that it would be a challenge for Canada to ratify the new North American free trade agreement with the tariffs still in place.