Exxon Mobil sued California’s attorney general, the Sierra Club and other environmental groups Monday, alleging that they conspired to defame the oil giant and kneecap its business prospects amid a debate over whether plastics can be recycled effectively.

The claims are an escalation in the legal conflict between oil companies and environmental groups, which have spent years fighting over environmental concerns related to fossil fuels, plastics and climate change.

Exxon’s lawsuit singles out language used by Rob Bonta, the California attorney general, who sued Exxon in September, alleging that the company carried out a “campaign of deception” that led people to buy more single-use plastics by promoting the idea that the products could be recycled. Plastics are made from fossil fuels and are more difficult to recycle than other materials like paper and metal. Bonta’s lawsuit, filed in superior court in San Francisco, denounced the company’s “advanced recycling” program, which refers to processes that break down plastics to create new materials, including fuel.

“Exxon Mobil has not engaged in a decades-long secret mission to brainwash or deceive the public,” the company said in its federal lawsuit, filed Monday in the Eastern District of Texas.

Exxon said Bonta later made false statements in interviews and other forums about the efficacy of its recycling technology, causing prospective business deals to fall apart. “Advanced recycling is not a ‘farce’ or ‘myth,’” the company said in its suit.

A spokesperson for the California Department of Justice called the suit “another attempt from Exxon Mobil to deflect attention from its own unlawful deception” and said Bonta was looking forward to “vigorously litigating” the case.

Exxon is seeking monetary damages, as well as retractions from Bonta and the environmental groups.

Representatives of the Sierra Club and the other groups named in the suit — San Francisco Baykeeper, Heal the Bay and the Surfrider Foundation, all based in California — did not immediately respond to requests for comment Monday. Those groups had filed their own lawsuit against Exxon in parallel with Bonta’s, alleging violations of state nuisance and unfair-competition laws.

An Australian charity, Intergenerational Environment Justice Fund, was also named in Monday’s lawsuit. That group is described in the suit as working on behalf of Andrew Forrest, the founder of an Australian mining company, Fortescue Metals Group, that has become a critic of Exxon. Exxon said the charity had retained a law firm, Cotchett, Pitre and McCarthy, and recruited the environmental groups that filed the parallel lawsuit as “proxies.”

The charity said in a statement Tuesday that it was not a subsidiary of, owned or controlled by Fortescue or Forrest’s environmental foundation, Minderoo. A spokesperson for Minderoo said that its work had been described incorrectly in Monday’s lawsuit.

Niall McCarthy, a partner with Cotchett, Pitre & McCarthy, called the case “a PR campaign” with no merit and said the groups stood by the lawsuits. “Suggesting they are anyone’s ‘proxy’ is baseless and fails to recognize that these nonprofits have been at the forefront of the battle over plastics,” he said.

Fortescue advocates transitioning away from oil and instead using hydrogen as fuel. Exxon in its lawsuit described the company as a competitor in the energy-transition sector. A spokesperson for Fortescue said Tuesday that it rejected Exxon’s assertions, including that the company had orchestrated the litigation to gain a competitive advantage.

Forrest, in a separate statement, said that “any accusation of commercial benefit” related to the case was false and that the fossil fuel industry knows it is “on borrowed time and that technological solutions exist to phase out fossil fuels.”

The September lawsuit by Bonta came after a more than two-year investigation that included subpoenas to Exxon and industry groups and sought damages that he said could amount to “multiple billions of dollars.”

Energy companies are facing numerous lawsuits from state and local governments, including California, alleging that they misled the public about climate change in their quest to keep selling fossil fuels. California’s plastics lawsuit had indicated a new tack in that yearslong legal battle and was built on a similar premise over claims of deception.

In a recent report, “The Fraud of Plastic Recycling,” the advocacy group Center for Climate Integrity concluded that recycling plastics had largely failed because it was too expensive to do on a large scale.