WASHINGTON - The governor of the US state of South Carolina, who had been missing for a week, finally turned up Wedensday and admitted to an affair with an Argentinian woman.

Mark Sanford, a Republican, vanished June 18 without telling either his family or staff where he was headed. In a press conference after his return Wednesday morning, Sanford said he went to Buenos Aires to end an affair with an Argentinian woman.

“The bottom line is this: I’ve been unfaithful to my wife,” Sanford said with tears in his eyes. “I hurt my wife, I hurt my boys.”

Sanford, once considered a potential presidential candidate, said he would resign as head of the Republican Party’s governors’ association. But he gave no clues as to whether he would resign as governor of South Carolina.

Sanford said he had known the Argentinian woman, who was not named, for about eight years, but the affair began one year ago. His wife Jenna had known for about five months.

“Forgiveness is not an immediate process,” Sanford said. He did not tell reporters whether his wife was seeking a divorce.

Sanford’s disappearance had attracted national media attention and sharp criticism from politicians in the state. The CNN Tuesday interviewed Jenna Sanford who said she, too, did not know her husband’s whereabouts.

“I am being a mom today. I have not heard from my husband,” said Jenna, who was not at her husband’s side Wednesday.

Sanford’s staff Tuesday said they believed he was hiking the Appalachian Trail, which runs along the East Coast of the United States. The governor acknowledged he may have misled his staff, telling reporters it was “my fault in shrouding this larger trip”.

Opposition Democrats in the state had jumped on the story of his disappearance, soliciting questions for Sanford from constituents on their website.

“They have a right to ask the governor about our state’s unemployment rate, the stimulus and his reasons for abandoning the state,” said Carol Fowler, who heads the Democratic Party in South Carolina.

South Carolina’s The State newspaper caught Sanford returning Wednesday morning at the airport in Atlanta, Georgia. At the time he told the paper he travelled to Buenos Aires to get “a break” after a hectic legislative session.

“I wanted to do something exotic … It’s a great city,” Sanford said. “I don’t know how this thing got blown out of proportion.”