Attorney General Jeff Sessions holds his first meeting with heads of federal law enforcement components at the Justice Department, in Washington, D.C., Feb. 9, 2017. REUTERS

The American Civil Liberties Union (ACLU) has demanded an investigation into whether Attorney general Jeff Sessions committed perjury when he testified under oath about having any communications with Russians during Donald Trump's successful presidential campaign. The former Alabama senator and recently confirmed top law enforcement official in the U.S. had secret contact with a Russian ambassador in July and September, the Washington Post reported late Wednesday.

Sessions has remained steadfast in his denials those meetings ever happened, including during his confirmation when he was pressed by Minnesota Sen. Al Franken about his alleged ties to Russia.

"Jeff Sessions took an oath before the Senate Judiciary Committee to tell the truth, the whole truth, and nothing but the truth, and it is now clear that he broke that oath in his confirmation hearing," ACLU Executive Director Anthony D. Romero said in part in a statement Thursday. "The American people deserve a full investigation into whether Sessions perjured himself and if he is indeed fit to serve as our nation’s highest law enforcement official. No one is above the law — certainly not those sworn to uphold it."

Merriam-Webster defined the word perjury as "the voluntary violation of an oath or vow either by swearing to what is untrue or by omission to do what has been promised under oath."

If it does turn out that Sessions was in contact with Russian ambassador Sergey Kislyak, it would appear that he did commit perjury during his Senate confirmation hearings in January when he told Franken the following: "I am not aware of any of those activities. I have been called a surrogate at a time or two in that campaign, and I did not have communications with the Russians, and I am unable to comment on it."

Sessions has previously agreed that perjury is unacceptable. When former President Bill Clinton was impeached in part over claims he committed perjury pertaining to an investigation into an extramarital affair he had with a White House intern, Sessions said on C-SPAN that "In America, the Supreme Court and the American people believe no one is above the law."

Sessions could face legal repercussions if he was found to have perjured himself. Top Democrats and a handful of Republicans have joined the chorus of calls for an investigation and for the attorney general to step down over the allegations.

Now-former National Security Adviser Mike Flynn resigned last week after it was shown he misled Vice President Mike Pence about his contact with Russian officials during Trump's campaign. Russia was found to have influenced the presidential election, national intelligence officials said after concluding their investigation.