(Reuters) - A group of Republican-led U.S. states filed a lawsuit seeking to block the U.S. Equal Employment Opportunity Commission from enforcing broad legal protections for transgender workers.

The 18 states filed the complaint in federal court in Knoxville, Tennessee, late Monday. They said the federal workplace bias agency lacked the power to assert that federal law requires employers to use transgender workers' preferred pronouns and allow them to use bathrooms that match their gender identity.

The commission last month updated its guidance on workplace harassment for the first time in 25 years, including positions that reflect a 2020 U.S. Supreme Court ruling that said discriminating against gay and transgender workers is a form of unlawful sex bias.

The EEOC in the guidance said denying accommodations to transgender workers amounts to workplace harassment based on sex.

But the states in their lawsuit said federal law is much narrower, protecting workers from being fired because they are transgender but not requiring employers to take affirmative steps to accommodate them.

"EEOC has no authority to resolve these highly controversial and localized issues, which are properly reserved for Congress and the states," they said.

A spokesman for the commission did not immediately respond to a request for comment.

Guidance is meant to direct the enforcement activities of EEOC staff, who investigate worker complaints and can broker settlements or file lawsuits against employers, and is not legally binding. Agencies have argued in past cases that enforcement guidance cannot be reviewed in court.

But the states in Monday's lawsuit said the commission's guidance marks a significant change in the agency's reading of federal law and will force some employers to change practices to avoid EEOC complaints and lawsuits by workers.

The states also claim that the guidance is invalid because the commission's structure as an independent agency violates the U.S. Constitution. They say that the U.S. president, who appoints the EEOC's five commissioners, should be able to remove them at will.

A mostly identical group of states also made those claims in a lawsuit filed last month challenging an EEOC rule that gives workers who have abortions the same legal protections as those who are pregnant or recently gave birth.

Monday's lawsuit is led by Tennessee and joined by Alabama, Georgia, Indiana, Missouri, Ohio, South Carolina, and Virginia, among other states.