US regulators on Thursday approved a controversial trade deal with Mexico that imposes a quota on sugar imports and sets minimum prices, rejecting challenges from domestic cane refiners and bringing a year-long trade battle closer to resolution. The decision by the US International Trade Commission paved the way for a suspension agreement between the US and Mexican governments that establishes floor values and puts a caps on volumes for imports from Mexico. The commissioners voted 6-0 in favour of the agreement, responding to challenges from two US refiners, Louis Dreyfus Commodities' Imperial Sugar Co and AmCane Sugar LLC, that said they would be harmed by the agreed-upon restrictions. The dispute has roiled North American trade flows of the sweetener since late March 2014, when a group representing US sugar companies and growers petitioned the US government for anti-dumping, anti-subsidy duties. The refiners have separately requested the US Department of Commerce continue the investigation, which was suspended when the pact was finalised in late December. The agency has not yet decided on whether the two companies, neither of which was on the original petition, are in a position to make that request. Lawyers for Imperial and AmCane did not respond immediately to calls for comment.