A federal judge in Seattle has temporarily blocked enforcement of a new Washington state law that would require classified advertising companies to verify the ages of people in sex-related advertisements.

On Tuesday, U.S. District Judge Ricardo Martinez granted a 14-day temporary restraining order sought by the website Backpage.com. Backpage filed suit this week to block the law pending a judge's decision on whether it should be struck down. The law was due to take effect Thursday.

Backpage contends the law is invalid.

Gov. Chris Gregoire signed the bill into law in an effort to cut down on child sex trafficking. It allows for the criminal prosecution of classified advertising company representatives who publish or cause publication of sex-related ads peddling children.

Backpage is a primary target of the law.

State Attorney General Rob McKenna says he will "forcefully defend this groundbreaking law."