Traders from across the U.S. are banding together to accuse J. P. Morgan Chase of manipulating precious metals markets for years.

At least six lawsuits, all making similar allegations against the nation's largest bank, have been filed in New York federal court in the past month, since federal prosecutors in Connecticut unveiled a plea agreement with a former J. P. Morgan Chase metals trader.

The cases could potentially include thousands of people who traded in the precious metals market. The White Plains, N.Y., law firm Lowey Dannenberg is asking the court to combine the cases and name it as the lead.

The law firm's commodities group is led by Vincent Briganti, the attorney who filed the first lawsuit on behalf of Dominick Cognata, a New York resident who alleges he suffered losses due to J. P. Morgan's trading conduct in the silver and gold futures and options markets.

A combined case, seeking class action status, would include anyone who purchased or sold futures contracts or an option on NYMEX platinum or palladium or COMEX silver or gold between at least Jan. 1, 2009, and Dec. 31, 2015. The lawyers believe that "at least hundreds, if not thousands" of traders would be eligible to join the case.

Named as defendants in all of the lawsuits are John Edmonds, a 36-year old former metals trader at J. P. Morgan, a group of yet-to-be-identified precious metals traders and the bank.

Edmonds, a New York resident, pleaded guilty in October to one count of conspiracy to defraud the market and manipulate prices of precious metals futures contracts and one count of commodities fraud. In the criminal plea, Edmonds admitted that he and other "unnamed co-conspirators" at J. P. Morgan, fraudulently manipulated precious metals markets from 2009 to 2015, the same time frame covered in the class action suits.

Briganti filed the initial class action on Nov. 7, just one day after the Justice Department unsealed Edmonds' plea in the U.S. District Court of Connecticut.

Edmonds admitted in his guilty plea that he deployed the illegal trading scheme hundreds of times with the direct knowledge and consent of his immediate supervisors. Plaintiffs say they have suffered economic injury, including monetary losses, as a direct result of actions by Edmonds and the other unnamed J. P. Morgan metals traders in the futures and options contracts.

One of the suits alleges that "the number of unlawful trades that JP Morgan traders executed in precious metals futures markets is at least in the thousands."

J. P. Morgan declined to comment. Lowey Dannenberg did not respond to a request for comment by CNBC.

The Justice Department's criminal investigation is still ongoing and recently caused a separate related civil case to be put on hold for at least six months while the government continues its investigation. That civil lawsuit, which also accuses J. P. Morgan of rigging the precious metals market, was filed in 2015 by hedge fund manager Daniel Shak and two commodity traders.

After reviewing the details of the plea agreement, David Kovel, the attorney for Shak's suit, sought to re-interview Edmonds, along with two other current and former senior traders at the bank. However, the government argued that reopening questioning would be detrimental to the ongoing criminal investigation. The federal judge overseeing the proceedings ordered a six-month stay in the civil case.

Kovel declined to comment.

Edmonds was originally scheduled to be sentenced in Hartford, Conn., on Wednesday, Dec. 19, but a court filing on Nov. 27 shows the sentencing has been postponed until June. A spokesman for the U.S. Attorney for Connecticut could not elaborate on why the sentencing was postponed since the court filing is under seal.