WASHINGTON — The Justice Department is investigating the fake slates of electors that falsely declared Donald J. Trump the victor of the 2020 election in seven swing states that Joseph R. Biden Jr. had in fact won, a top agency official said on Tuesday.

“Our prosecutors are looking at those, and I can’t say anything more on ongoing investigations,” Lisa O. Monaco, the deputy attorney general, said in an interview with CNN.

The false certificates appear to have been part of an effort by Mr. Trump’s allies to reverse his defeat in the presidential election. Even as election officials in the seven contested states sent official lists of electors who had voted for Mr. Biden to the Electoral College, the fake slates claimed Mr. Trump was the winner in an apparent bid to subvert the election outcome.

Lawmakers, state officials and the House committee investigating the Jan. 6 riot have asked the Justice Department to look into the role played by those fake electors and the documents they submitted to the National Archives on Dec. 14, 2020.

In some cases, top Republican Party officials in those seven states signed the false documents, according to copies posted online last March by American Oversight, a nonprofit watchdog group.

“The phony electors were part of the plan to create chaos on Jan. 6, as a pretext for a contingent election,” said Representative Jamie Raskin, Democrat of Maryland and a member of the committee.

“The fake electoral slates were an effort to create the illusion of contested state results,” Mr. Raskin said. That, he added, would have given Mike Pence, who as vice president presided over Congress’s count of electoral votes on Jan. 6, “a pretext for unilateral rejection of electors.”

In Michigan, Dana Nessel, the attorney general, gave federal prosecutors information from her yearlong investigation into the matter. She has said that she believes there is enough evidence to charge 16 Republicans in her state with submitting the fake certificates and falsely claiming that they were official electors for the state.

And Hector Balderas Jr., the attorney general of New Mexico, and a local prosecutor in Wisconsin also asked the Justice Department to review the matter.

If investigators determine that Mr. Trump’s allies created the fake slates to improperly influence the election, they could in theory be charged with falsifying voting documents, mail fraud or even a conspiracy to defraud the United States.

It is unclear whether the Republican Party officials and others who submitted the false documents did so on their own or at the behest of the Trump campaign.

“The people who pretended to be official electors in states that were won by Biden were undoubtedly guilty of fraud on the Constitution and on the democracy,” Mr. Raskin said. “It’s a trickier question whether they are guilty of either common-law fraud, state statutory fraud, federal mail fraud or some other offense.”

Luke Broadwater contributed reporting.