WASHINGTON, June 24 (Xinhua) -- A U.S. governor who has gained media attention by his four-day disappearance admitted on Wednesday that he has been having an extramarital affair.

South Carolina Governor Mark Sanford wipes his eyes as he speaks to the media about his trip to Buenos Aires and admits to an extramarital affair at the State House in Columbia, June 24, 2009. (Xinhua/Reuters Photo) Photo Gallery>>>

    "I've been unfaithful to my wife," said South Carolina Governor Mark Sanford at a press conference. "I developed a relationship with what started as a dear, dear friend from Argentina."

    Sanford disclosed that he has been on a trip to Argentina during the four days of disappearance last week, not hiking on the Appalachian Trail as his staff originally said.

    "I've let down a lot of people," he said in a statement, apologizing to his wife, staff and South Carolina people.

    Sanford also announced his intention to resign as the chairman of the Republican Governors' Association, however, without saying if he would leave the office as a governor.

    According to the 49-year-old married father, he met the Argentina woman about eight years ago and developed a romantic relation with her about one year ago. His wife, Jenny Sanford, and family became aware of his affairs five months ago.

South Carolina Governor Mark Sanford tries to compose himself as he speaks to the media about his trip to Buenos Aires and admits to an extramarital affair at the State House in Columbia, June 24, 2009.(Xinhua/Reuters Photo) Photo Gallery>>>

    "I met this person a little over eight years ago, very innocently ... What I did was wrong. Period. End of story," he said.

    First elected governor in 2002, the former real estate developer has been considered a potential candidate for the 2012 presidential campaign. He has more than one year left in his second term and is barred by state law from running again.

    Sanford's confession came a day after another prominent Republican, Senator John Ensign of Nevada, apologized to his Republican Senate colleagues for his affair.

    Ensign revealed last week that he had a romantic relationship with a campaign staffer and was resigning from the Republican leadership in the Senate.