New Jersey's acting attorney general confirmed Thursday that the state had reached a settlement agreement with ExxonMobil Corp. over decades of contamination in North Jersey, but the announcement was overshadowed by allegations that a top aide to Gov. Christie meddled in the litigation and criticism that the deal shortchanged taxpayers and the environment.

The proposed $225 million settlement, reached after state prosecutors sought $8.9 billion in damages at trial last year, is expected to be published in the New Jersey Register on April 6.

It would then be subject to a 30-day comment period and must be approved by a state judge.

Christie administration officials called it the "single largest environmental settlement with a corporate defendant in New Jersey history."

Acting Attorney General John J. Hoffman said that in addition to paying the settlement, ExxonMobil agreed to remediate refinery sites in Linden and Bayonne that had polluted 1,500 acres of state land.

The settlement "ensures the continuation of the ExxonMobil-funded remediation work at these contaminated sites, and it holds the company financially accountable," Hoffman said.

Lawmakers and environmentalists have been criticizing the settlement since terms leaked last week.

In a commentary published Thursday in the New York Times, Bradley M. Campbell, a former commissioner of the New Jersey Department of Environmental Protection who authorized the lawsuit against ExxonMobil in 2004, called the settlement a "disgrace" and an "embarrassment to law enforcement and good government."

He said former colleagues in state government had told him that Christopher Porrino, the governor's chief counsel, "elbowed aside the attorney general and career employees who had developed and prosecuted the litigation, and cut the deal favorable to Exxon."

Kevin Roberts, a spokesman for the Republican governor, called the allegations "baseless" and dismissed Campbell as a "known partisan" who had worked for Democrats.

Hoffman's office said Thursday that "the litigation and settlement negotiations, as with all such cases of this magnitude, were conducted" by the Attorney General's Office in coordination with the Department of Environmental Protection and the Governor's Office.

He said "settling the case rather than continuing to litigate provides a predictable, fair outcome for the people of New Jersey."

The allegation of interference by Christie's office comes as state lawmakers have vowed to scuttle the settlement in court and hold a public hearing to determine what happened.

"If what is alleged took place, then this is much bigger than any kind of litigation, and it's a subject matter for [U.S. Attorney] Paul Fishman," Senate President Stephen Sweeney (D., Gloucester) said during a conference call with reporters Thursday.

First, Sweeney cautioned, "we've got to find out if what's alleged is true."

Edward Lloyd, a professor of environmental law at Columbia University Law School, said the state either was wrong in initially claiming nearly $9 billion in damages or for settling for so much less.

"I don't think you can have both judgments be accurate," he said. "It doesn't sound plausible."

The timing of the settlement also seemed strange, Lloyd said.

"There are times in the life of a case when a settlement is really opportune, but that doesn't seem to be the case here," Lloyd said. "You've done all the work. The case is in; it's in front of the judge. Why all of a sudden do you think the judge is going to discount your claim by 95 percent?"

"If you thought that," he added, "why wasn't the case settled five years ago, for instance?"

Campbell's allegation of interference by Christie's office also raised questions about the independence of the Attorney General's Office. Although Hoffman has led the office since June 2013, Christie has not nominated him to be confirmed by the Democratic-controlled Senate.

Christie previously chose his former chief of staff, Kevin O'Dowd, for the job. But the nomination did not proceed amid the George Washington Bridge lane-closure scandal, which erupted in January 2014. O'Dowd, who was not accused of any wrongdoing, left the administration last year to work for Cooper University Hospital in Camden.

The 2004 environmental lawsuit alleged that for decades, ExxonMobil's plants and refineries in Linden and Bayonne contaminated the state's wetlands, marshes, and creeks.

The case finally moved to trial last year, and all that was left to determine was what ExxonMobil owed in damages.

The judge was apparently close to issuing a ruling. But in January, the state asked the judge to delay a decision so that settlement talks could proceed, the New York Times reported last week.

Environmentalists accused Christie, a Republican considering running for president in 2016, of quickly securing the settlement so he could divert money to the general fund.

"The administration had no reason to settle, other than balancing the budget and giving away the store to Exxon at the expense of New Jersey's environment," said Jeff Tittel, director of the New Jersey Sierra Club.

"This is a bigger scandal than Bridgegate," Tittel added. "Bridgegate was about retribution. This settlement is costing the taxpayers billions of dollars. When you sell out the public and let the polluters off the hook, it sends a message that you can get away with anything in the Christie administration."

Under the appropriations bill Christie signed in June, the first $50 million the state obtains "in natural resource, cost recoveries and other associated damages" must be deposited into a fund for hazardous discharge cleanup.

But the law says all money obtained beyond that "shall" be diverted to the general fund. Democrats had sought to allocate half of such money - beyond the initial $50 million - to environmental programs, but Christie vetoed that language.

Hoffman said Thursday that the state wouldn't receive settlement money until fiscal 2016 at the earliest. The funds would be allocated in accordance with the appropriations act for that fiscal year, which begins July 1.

Records filed with the IRS show ExxonMobil donated $500,000 to the Republican Governors Association in 2014, when Christie chaired the group and raised record sums to help elect GOP governors across the country. The company had made contributions to the RGA in previous years, including more than $600,000 in 2010, records show.

ExxonMobil spokesman Alan Jeffers said the company also donated to the Democratic Governors Association. Christie's position as RGA chairman last year "had no bearing on our decision to donate or the amount donated," he said.

Under the proposed settlement, New Jersey maintains its claims against ExxonMobil for contamination at other sites, the Attorney General's Office said.