(Reuters) -Social media platform Reddit ( RDDT ) sued artificial intelligence startup Perplexity in New York federal court on Wednesday, accusing it and three other companies of unlawfully scraping its data to train Perplexity's AI-based search engine.

Reddit ( RDDT ) said in the complaint that the data-scraping companies circumvented its data protection measures in order to steal data that Perplexity "desperately needs" to power its "answer engine" system.

The case is one of many filed by content owners against tech companies over the alleged misuse of their copyrighted material to train AI systems. Reddit ( RDDT ) filed a similar lawsuit against AI startup Anthropic in June that is still ongoing. 

"Our approach remains principled and responsible as we provide factual answers with accurate AI, and we will not tolerate threats against openness and the public interest," Perplexity said in a statement.

"AI companies are locked in an arms race for quality human content-and that pressure has fueled an industrial-scale 'data laundering' economy," Reddit ( RDDT ) chief legal officer Ben Lee said in a statement. 

Reddit ( RDDT ), which features thousands of interest-based "subreddit" web communities, said in the lawsuit that it is the most commonly cited source for AI-generated answers to user questions. It has licensed its content to Google, OpenAI and others for their AI training. 

Reddit ( RDDT ) said that Lithuania-based Oxylabs, Russia-based AWMProxy and Texas-based SerpApi scraped Reddit ( RDDT ) data from billions of search results without permission and that Perplexity, which does not have a license to use Reddit ( RDDT ) content, worked with at least one of the data-scraping companies to obtain Reddit ( RDDT ) material.

Spokespeople for Oxylabs and SerpApi did not immediately respond to requests for comment on the case. AWMProxy could not be reached for comment.

Reddit ( RDDT ) said it sent Perplexity a cease-and-desist letter last year, after which it "increased the volume of citations to Reddit ( RDDT ) forty-fold."

Reddit ( RDDT ) asked the court for unspecified monetary damages and an order blocking Perplexity from using its data.