Will also investigate whether producers in Canada, China and Mexico are receiving unfair subsidies.
US department of Commerce claims Canadian exporters underpriced uncoated groundwood paper by between 0 and 22.16%.
Industry analysts expect preliminary countervailing duties will be imposed on aircraft deliveries to the US.
Department of Commerce claims US industry damaged by subsidized Canadian imports.
Port Hawkesbury Paper calls interim duty of 20.33% by the US Department of Commerce unfair and without merit.