Amazon.com Inc. won partial dismissal of a U.S. Federal Trade Commission's lawsuit accusing it of maintaining illegal monopolies, though the details of the ruling by a federal court in Seattle on Monday were not immediately clear.

The FTC has accused the online retailer of using anti-competitive tactics to maintain dominance among online superstores and marketplaces. Amazon asked U.S. District Judge John Chun to dismiss the case in December, saying the FTC had raised no evidence of harm to consumers.

Chun issued a sealed ruling, partially granting Amazon's motion. The FTC will be allowed to continue to pursue any claims the judge did not permanently dismiss, court records showed.

Chun also ruled the case will be tried in two parts, rejecting Amazon's bid to have the FTC present evidence of the alleged violations and its proposed remedies in the same trial.