Attorney General Jeff Sessions. (Screenshot: CSPAN, YouTube)

(CNSNews.com) -- A Department of Justice spokesman said the agency is "reviewing" a letter from Senate Judiciary Chairman Charles Grassley (R-Iowa) to Attorney General Jeff Sessions, requesting that the department lift the gag order on a former FBI informant who helped in a Russian bribery case involving uranium and who reportedly has information about how Russians allegedly helped facilitate the Obama administration's 2010 approval of the sale of Uranium One to Rosatom, which gave Russia control over 20% of U.S. uranium production.

In addition, the former informant reportedly has information on alleged Russian nuclear industry payoffs to a group assisting the Clinton Foundation. In the 2010 sale, then-Secretary of State Hillary Clinton served on the committee that approved the deal, as did Attorney General Eric Holder.

CNSNews.com asked the DOJ if Attorney General Sessions will lift the gag order -- a Non-Disclosure Agreement (NDA) the informant had to sign -- and if so, when will this occur? A DOJ spokesman answered by email that the department is still "reviewing" the letter from Sen. Grassley.

Charles Grassley (R-Iowa), chairman of the Senate Judiciary Committee. (Screenshot: YouTube)

In an Oct. 19 statement, Sen. Grassley's office said that the senator "is calling on the Justice Department to lift a reported non-disclosure agreement preventing a former FBI confidential informant from speaking to Congress about the handling of a criminal probe linked to a controversial deal that ceded ownership of U.S. uranium assets to the Russian government."

"Despite an ongoing criminal investigation into officials working for subsidiaries of Rosatom, the Russian government entity seeking to acquire ownership of U.S. uranium," reads the statement, "the Obama Administration approved the deal. The Justice Department has reportedly threatened to prosecute the informant if he discloses details of his involvement in the investigation."

Grassley himself said, “The Executive Branch does not have the authority to use non-disclosure agreements to avoid Congressional scrutiny. If the FBI is allowed to contract itself out of Congressional oversight, it would seriously undermine our Constitutional system of checks and balances."

"The Justice Department needs to work with the Committee to ensure that witnesses are free to speak without fear, intimidation or retaliation from law enforcement," he said. "Witnesses who want to talk to Congress should not be gagged and threatened with prosecution for talking. If that has happened, senior DOJ leadership needs to fix it and release the witness from the gag order."

The former confidential informant wants to speak with members of Congress about what he heard and learned while working on a 2009-2014 case involving a subsidiary of Rosatom and a Russian national who was receiving kickbacks in exchange for bid-free contracts to transport uranium to the United States. (More on the legal case here.)

The informant's lawyer, Victoria Toensing, told CNSNews.com that the DOJ in the Obama administration warned the informant that if he violated the NDA, "he would lose his liberty."

Toensing further said "the Obama administration did not comply with a FOIA request from my client's" previous attorney, and that "the FBI did not give him a copy [of the NDA] when he signed it."

President Bill Clinton. (YouTube)

The informant was working undercover for the FBI when the Obama administration, through the Committee on Foreign Investment in the United States (CFIUS), approved the sale of Uranium One to Rosatom in October 2010.

The Hill reported on Oct. 18, "Toensing said her client can also testify that FBI agents made comments to him suggesting political pressure was exerted during the Justice Department probe of the Russia corruption case and that there was specific evidence that could have scuttled approval of the Uranium One deal if it became public."

“'There was corruption going on and it was never brought forward,'" Toensing told The Hill. "'And in fact, the sale of the uranium went on despite the government knowing about all of this corruption. So he's coming forward. He wants the right thing to be done, but he cannot do it unless he is released from the NDA,' she added."

In the kickback case the informant was involved in, one of the prosecuting attorneys was Rod J. Rosenstein, who is now the deputy attorney general of the United States. One of the FBI officials involved was Andrew McCabe, who is now the deputy FBI director. During the investigation, 2009-2014, Robert Mueller was the FBI director until September 2013, when James Comey became the FBI director.

President Barack Obama and the president of Khazakhstan, Nursultan Nazarbayev. (YouTube)

Robert Mueller is now the Special Counsel investigating the Trump presidential campaign for alleged collusion with Russia. Mueller was appointed to his position by Rod J. Rosenstein.

In closing his letter to Attorney General Jeff Sessions, Senator Grassley wrote, "This Committee has oversight jurisdiction of the Justice Department, and if this NDA [Non-Disclosure Agreement] does in fact exist, it hinders the Committee’s ability to do its job. Accordingly, please provide a copy of the NDA by November 1, 2017. In addition, should the NDA exist, I request that you release him from it and pledge not to engage in any form of retaliation against him for good faith communications with Congress."