(Reuters) -Amazon sued Perplexity AI on Tuesday over the startup's "agentic" shopping feature, which uses automation to place orders for users, saying it covertly accessed Amazon customer accounts and disguised automated activity as human browsing.

The clash highlights an emerging debate over regulation of the growing use of AI agents and their interaction with websites, aiming to make them more autonomous and capable of handling everyday online tasks.

Perplexity, which has grown rapidly amid the boom in AI assistants, has previously rejected the U.S. shopping giant's claims, saying it was using its market dominance to stifle competition.

The startup did not immediately respond to a Reuters request for comment on Amazon's lawsuit filed in the U.S. District Court for the northern district of California.

AMAZON WANTS PERPLEXITY TO END 'MISCONDUCT'

In the suit, Amazon accused Perplexity of covertly accessing private Amazon customer accounts through its Comet browser and associated AI agent, and of disguising automated activity as human browsing.

Perplexity's system posed security risks to customer data, Amazon added, and the startup had ignored repeated requests to stop.

"Rather than be transparent, Perplexity has purposely configured its CometAI software to not identify the Comet AI agent's activities in the Amazon Store," it said. 

"Perplexity's misconduct must end," Amazon added. "Perplexity is not allowed to go where it has been expressly told it cannot; that Perplexity's trespass involves code rather than a lockpick makes it no less unlawful." 

Perplexity earlier said it had received a legal threat from Amazon demanding that it block the Comet AI agent from shopping on the platform, calling the move a broader threat to user choice and the future of AI assistants.

"Bullying is when large corporations use legal threats and intimidation to block innovation and make life worse for people," the company wrote in a blog post.

In the complaint, Amazon accused Perplexity's Comet AI agent of degrading customers' shopping experience and interfering with its ability to ensure customers who use the agent benefit from the tailored shopping experience Amazon curated over decades. 

Third-party apps making purchases for users should operate openly and respect businesses' decisions on whether to participate, Amazon said in an earlier statement.

CREDENTIALS STORED LOCALLY, SAYS PERPLEXITY

Perplexity is among many AI startups seeking to reinvent the web browser around artificial intelligence, aiming to make it more autonomous and capable of handling everyday online activities, from drafting emails to completing purchases.

Amazon is also developing similar tools, such as "Buy For Me", which lets users shop across brands within its app, and "Rufus", an AI assistant to recommend items and manage carts.

The AI agent on Perplexity's Comet browser acts as an assistant that can make purchases and comparisons for users. The company said user credentials remain stored locally and never on its servers.

"Easier shopping means more transactions and happier customers," it added. "But Amazon doesn't care, they're more interested in serving you ads."

The startup said users had the right to choose their own AI assistants, portraying Amazon's move as a bid to protect its ad-driven business model.