The U.S. Commerce Department announced Monday that it has decided to once again apply tariffs on fabricated steel imports from Mexico.

A staff works in a steel factory. [File photo: IC]

In a statement, the U.S. agency said the decision came after an investigation into government subsidies assisting companies that export fabricated structural steel from Mexico, China and Canada. The agency said it determined Canadian exports do not warrant the tariff, but those from Mexico and China do.

Mexico's economy ministry said the decision was unrelated to tariffs that the U.S. lifted on Mexican steel and aluminum May 20 or to President Donald Trump's since rescinded threat to put tariffs on all Mexican exports to the U.S.

The Commerce Department said the determination is preliminary, but the tariff goes into effect immediately.

The Chicago-based American Institute of Steel Construction Full Member Subgroup requested the investigation.