California attorney general Rob Bonta has asked a state court for a preliminary injunction in the state’s existing antitrust case against Amazon to prevent the company’s alleged campaign of pushing merchants not to sell goods more cheaply on other platforms.

In a heavily redacted filing, the state requested that Amazon be enjoined from explicit price-fixing with its vendors and competitors and from communicating with vendors about other retailers’ pricing.

The state is also seeking to enjoin Amazon from coercing vendors to serve as a go-between with competing sales platforms by demanding money to meet Amazon’s costs for price-matching a lower-priced retailer.

The motion also requests for a monitor to be put in place to ensure Amazon complies with the injunction.

Bonta said in the filing that Amazon was seeking to “insulate itself from price competition” and was telling vendors “what prices it wants to see to maintain its own profitability”.

He said his office has uncovered “countless” interactions in which Amazon agreed with competing platforms and merchants to fix prices to ensure Amazon would not be undercut on platforms such as eBay, Target and Walmart.

Merchants acted as intermediaries with Amazon competitors to agree to raise prices or make products temporarily unavailable so that Amazon would not have to price-match, Bonta claimed.

Vendors who did not comply would be cut off from key features on Amazon’s platform, he said.

Amazon has said in court papers that it has legal and “pro-competitive” agreements with merchants that are commonplace in the industry, and benefit consumers.