Updated

Recently discovered documents that seem to show that a contractor for the highly criticized classifieds website Backpage.com solicited and created sex-related ads on behalf of the site go against often repeated claims by Backpage that it's never had a role in creating or developing third-party content on its site.

The documents seized from Avion, a Philippines-based company, show that Avion worked to promote and create sex ads on behalf of Backpage overseas. The documents reportedly show Avion lured advertisers, and customers seeking sex, from sites run by its competitors, The Washington Post reported. The seizure and contents of the documents, connected to an unrelated lawsuit in Kansas City, were first reported by NBC News.

Dallas-based Backpage.com has long been labeled by authorities as an online brothel, and a recent U.S. Senate report said the site is involved in 73 percent of all child trafficking reports that the National Center for Missing and Exploited Children receives from the public.

Backpage has defended its website by saying it doesn't have control over the sex-related ads. The company has also said it's protected by the U.S. Constitution and the federal Communications Decency Act, which grants immunity to websites that post content created by others. Various court rulings have upheld Backpage's defense claims. The company has also said it takes efforts to prevent illegal activity with warnings and filters that block and remove improper ads.

However, documents seized from Avion seem to go against claims by Backpage that it doesn't have a hand in creating content that goes on its site. Workers with Avion allegedly contacted people who had posted sex ads on rival sites and offered them freed ads on Backpage.com and even created the new ads, according to the documents, which included emails, spreadsheets, and employee manuals. Workers also allegedly created phony sex ads that were posted on competitors' websites and then used to direct someone who clicked on the ad to Backpage.com.

One manual that was seized provided Avion employees with instructions on how to find ads on other websites and copy them. The manuals suggested that other types of ads, such as for jobs, are also targeted, but the spreadsheets seized from Avion focused largely on sex ads.

Backpage general counsel Liz McDougall did not immediately return a phone call or email from The Associated Press seeking comment on Wednesday. A spokesperson for Avion also did not immediately return a call.

A U.S. Senate subcommittee report earlier this year called Backpage's public defense "a fiction." The report said Backpage continually altered ads before publication by deleting words, phrases and images indicative of criminality, including child sex trafficking. The report also alleged that Backpage is aware its site facilitates prostitution and child sex trafficking.

During a meeting in January of the Senate subcommittee, four top Backpage executives and the company's lawyer declined to testify, invoking their constitutional right against self-incrimination.

Backpage currently faces various criminal cases and civil lawsuits around the country.

On Wednesday, Backpage filed a federal lawsuit trying to block an investigation by Missouri Attorney General Josh Hawley.

"My message to Backpage is that there is no First Amendment right to engage in human trafficking," Hawley said. "And this frivolous lawsuit will not deter me from pursuing the eradication of this terrible crime in Missouri."

In California, a court hearing was scheduled for Friday on pimping and money laundering charges filed against site creators Michael Lacey and James Larkin and CEO Carl Ferrer. Prosecutors allege most of Backpage's revenue came from ads for paid sex.

In December, a judge — citing federal free-speech laws— threw out initial pimping charges that had been filed in the case.

The documents seized from the Philippines-based company were provided to NBC News and the Washington Post by an attorney who has filed a lawsuit in Chicago against Backpage, alleging the death of a 16-year-old was due to her becoming a sex trafficking victim who was featured in solicitation posts on Backpage.com.