On the orders of Attorney General Jeff Sessions, Justice Department prosecutors have begun asking FBI agents to explain the evidence they found in a now dormant criminal investigation into a controversial uranium deal that critics have linked to Bill and Hillary Clinton, multiple law enforcement officials told NBC News.

The interviews with FBI agents are part of the Justice Department's effort to fulfill a promise an assistant attorney general made to Congress last month to examine whether a special counsel was warranted to look into what has become known as the Uranium One deal, a senior Justice Department official said.

At issue is a 2010 transaction in which the Obama administration allowed the sale of U.S. uranium mining facilities to Russia's state atomic energy company. Hillary Clinton was secretary of state at the time, and the State Department was one of nine agencies that agreed to approve the deal after finding no threat to U.S. national security.

Hillary Clinton has denied playing any role in the decision by the State Department to approve the sale, and the State Department official who approved it has said Clinton did not intervene in the matter. That hasn't stopped some Republicans, including President Trump, from calling the arrangement corrupt — and urging that Clinton be investigated.

An FBI spokesman declined to comment.

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