Bayer AG’s comprehensive settlement of U.S. lawsuits over its Roundup weed killer is in jeopardy after lawyers for some consumers accused the company of reneging on the $11 billion deal and the judge overseeing the litigation questioned its truthfulness.

U.S. District Judge Vince Chhabria said during a hearing Thursday he’s concerned Bayer has “manipulated” the settlement process since announcing its plan in June to resolve 125,000 cases alleging that the herbicide causes cancer. He said he will revisit in a month whether to keep the litigation on hold for settlement talks to continue or to let more trials proceed.

“My concern is that if I leave the stay in place, am I complicit in whatever shenanigans are taking place on the Bayer side?” the judge said.

If the June deal were to break down, settlements of many cases would probably still move forward. Lawyers representing those plaintiffs expressed confidence in the negotiations.

Still, the hitches in the process create a new headache for the German pharmaceutical and chemical company just as it seemed to be moving on from a wave of litigation over Roundup and the Essure contraceptive device. The legal threat has weighed on Bayer since its 2018 acquisition of Monsanto, maker of the herbicide, with the shares losing more than a third of their value.

The stock traded 0.4% lower early Friday in Frankfurt.

Earlier Concerns

Only weeks after the Roundup settlement was announced in June, a proposed system for resolving future lawsuits was pulled after Chhabria raised objections to it. The company has appealed verdicts against it and says the product is safe.

Bayer said it remains optimistic about finalization of the deal.

“A mass tort settlement of this size and complexity can take significant time before it is fully executed, and we are still early in this process,” the company said in a statement. “There are often some bumps in the road in implementing a resolution of this magnitude, but we remain confident that a comprehensive settlement will be finalized and executed.”

Brent Wisner, one of the lead attorneys for consumers, told the judge “there is no settlement.” He urged Chhabria to lift a pause on the litigation because the process has hit a wall.

“At this point it’s become clear to me that when we were told we had an agreement, either they didn’t have authority to do that or they’ve reneged on it,” Wisner said.

The judge said he’s inclined to make public confidential letters from plaintiffs’ attorneys complaining that Monsanto, the maker of Roundup that Bayer acquired in 2018, is retreating from the settlement.

If Monsanto is “going back on its deal and the deal it announced in June, that seems to me something that should not be kept confidential,” Chhabria said, adding that it’s a matter “of significant public concern.”