Speaking at an event during Climate Week in New York City, California Attorney General Rob Bonta said the state sued Exxon after concluding a nearly two-year investigation that he said showed Exxon was deliberately misleading the public about the limitations of recycling.

"Today's lawsuit shows the fullest picture to date of ExxonMobil's decades-long deception, and we are asking the court to hold ExxonMobil fully accountable for its role in actively creating and exacerbating the plastics pollution crisis through its campaign of deception," Bonta said in a statement.

The investigation mirrors California's previous probes into the oil industry's alleged efforts to mislead the public about climate change, which the state is also suing over. The state has a long-standing adversarial relationship with Big Oil.

Once a major crude supplier, California's oil production has declined steadily for almost four decades, with companies saying the regulatory environment makes it a difficult place to invest.

Exxon rival Chevron Corp, a strong critic of California’s policies, said this year it plans to move its headquarters to oil friendly Texas from the state where it was founded. 

A coalition of environmental groups including the Sierra Club filed a related lawsuit in the same state court in San Francisco, raising similar allegations against Exxon.

Bonta, a Democrat, said his office specifically had sought information on Exxon's promotion of its "advanced recycling" technology, which uses a process called pyrolysis to turn hard-to-recycle plastic into fuel. 

He had said the technology's slow progress was a sign of Exxon's ongoing deception. He said he wants to secure an abatement fund and civil penalties for the harm inflicted by plastics pollution on California.

Exxon pushed back, arguing advanced recycling and similar solutions work and that California itself failed to correct problems in its recycling system.

"Instead of suing us, they could have worked with us to fix the problem and keep plastic out of landfills," said Lauren Kight, spokesperson for Exxon.

Kight said Exxon processed more than 60 million pounds of plastic waste into usable raw materials, keeping it out of landfills through advanced recycling.

Notre Dame Law School Professor Bruce Huber, who specializes in environmental law, said California may face an "uphill battle" with its lawsuit.

"The state's primary claim relies on public nuisance, a notoriously murky area of law. It could be difficult for a court to grant California relief here without opening a Pandora's box of other, similar claims," he said.

Exxon is the world's largest producer of resins used for single-use plastics, according to a report published last year by the Minderoo Foundation, with consultancies Wood Mackenzie and the Carbon Trust.

Reuters has reported on the enormous obstacles facing advanced recycling that the plastics industry touts as an environmental savior.

California's lawsuit comes ahead of a final round of global plastic treaty negotiations set to take place in Busan, South Korea, at the end of the year.

In those talks, countries are split over whether the treaty should call for caps on plastic production, a position opposed by Exxon and the global petrochemical industry.

The US last month said it supports a treaty designed around global plastic production cuts.

Environmental groups praised the lawsuit. Christy Leavitt, Oceana's plastics campaign director, said California's lawsuit will "hold industry accountable and debunk the plastics recycling narrative that holds us back from real solutions."