"My belief that I did not wear that costume or attend that party stems in part from my clear memory of other mistakes I made in the same period of my life", Northam said.
Ralph Northam, the governor of the USA state of Virginia, has vowed to remain in office despite widespread calls for his resignation after a racist photo surfaced in his yearbook page from more than 30 years ago.
Joan Naidorf, whose husband's page is opposite Northam's in the yearbook, said she was surprised the photos are only now coming out, given Northam's stature in Virginia politics.
The Virginian-Pilot newspaper tweeted a picture of the page which it said it obtained from the medical school library.
Northam's page in the 1984 yearbook from Eastern Virginia Medical School shows a picture of a person in blackface and another wearing a Ku Klux Klan hood.
"Earlier today, a website published a photograph of me from my 1984 medical school yearbook in a costume that is clearly racist and offensive", Northam said in an apology statement.
"I accept responsibility for my past actions and I am ready to do the hard work of regaining your trust", Mr Northam said.The organization's founder, Margaret Sanger, was an avowed eugenist who wrote in her autobiography that she "accepted an invitation to talk to the women's branch of the Ku Klux Klan".
In his statement, Northam said he recognized "that it will take time and serious effort to heal the damage this conduct has caused". Some believe that all blackface is offensive; but even if that's so, that just tells you that Northam, when he was 25, did something offensive. Fairfax is the second black person to be elected to statewide office in Virginia and has not publicly commented on the photograph. "It's time for Ralph to step down, and for the Commonwealth to move forward".
Northam, a folksy pediatric neurologist who is personal friends with many GOP lawmakers, has recently come under fire from Republicans who have accused him of backing infanticide after he said he supported a bill loosening restrictions on late-term abortions.
"I believe now and then that I am not either of the people in this photo", he said.
Friday evening there were growing calls for Northam's resignation.
High-profile Democrats, including former President Barack Obama and former Vice President Joe Biden, campaigned for Northam in 2017.
House Speaker Kirk Cox and Senate Majority Leader Tommy Norment said Saturday the governor had lost the public's confidence, and it is in the state's best interests for him to step down.
"Governor Northam has lost all moral authority and should resign immediately", former USA vice president Joe Biden, a Democrat weighing a 2020 presidential run, said on Twitter.
One of the figures is Northam, and he didn't say which one in an apology issued late Friday.
Democratic candidate for governor Ralph Northam speaks after his election night victory at the campus of George Mason University in Fairfax, Virginia, November 7, 2017.
"We are here today because the history of Jim Crow is still alive and living in the Governor Mansion", said community activist Art Burton, who also touched upon Richmond's racist roots as the capitol of the Confederacy during the Civil War.