SIOUX FALLS, S.D. (AP) — A national advocacy group ranks South Dakota's human trafficking laws as the weakest in the nation.

The Washington, D.C.-based Polaris Project says South Dakota lacks safe harbor laws for underage victims, doesn't require training on human trafficking for law officers, doesn't seize assets obtained through trafficking, hasn't lowered its burden of proof for sex crimes involving juveniles, and doesn't allow sex trafficking victims to easily purge prostitution convictions from their record.

Gov. Dennis Daugaard and Attorney General Marty Jackley say they see the report as an opportunity for improvement.

U.S. Attorney Brendan Johnson cautions against reading too much into the rankings. He says state and federal law enforcement work together closely in South Dakota, and any state-level trafficking cases are prosecuted under federal law, where the penalties are more severe.

Copyright 2013 The Associated Press.