June 24 (Bloomberg) -- South Carolina Governor Mark Sanford said he had been unfaithful to his wife and said he will resign as chairman of the Republican Governors’ Association.

Sanford, 49, spoke at a news conference today in Columbia after returning from a seven-day disappearance from the state. He said he has been involved with a person from Argentina.

The governor’s staff had said he was hiking the Appalachian Trail.

To contact the reporter on this story: Jonathan Salant in Washington at jsalant@bloomberg.net

Last Updated: June 24, 2009 14:36 EDT