Columbia, S.C. ? South Carolina Gov. Mark Sanford took dozens of undisclosed flights on private planes since taking office in 2003 despite a state law requiring him to report who paid for the travel, an Associated Press investigation has found.

The AP discovered 35 flights Sanford took on private planes that he did not list on state ethics forms or campaign reports. The flights are noted on Sanford’s official calendars, obtained by the AP through a Freedom of Information request.

State law requires elected officials to disclose gifts received in a day worth $25 or more and “anything of value” over the course of a year worth at least $200 “if there is reason to believe the donor would not give the thing of value” but for the public official’s position.

Sanford, under scrutiny since announcing an affair with an Argentine mistress, didn’t report the flights because the trips were paid for by longtime friends or political groups, spokesman Ben Fox said. “That was our standard operating procedure,” he said.

However, state ethics officials said Sanford should report all use of private planes, even if friends pick up the tab, just as any other public official is required to do under the law.

Cathy L. Hazelwood, the state Ethics Commission’s general counsel, said such flights “need to be disclosed somewhere.”

“To the extent friendship is a reason not to report something is fascinating to me,” she said. “There is no private Mark Sanford at this point.”

Sanford used the private planes, including some owned by supporters, to fly around the state for political functions, to attend sporting events with supporters and, at times, to go on vacation with his family, the calendars show. In one 2005 trip, the family took Sanford supporter J.T. Gandolfo’s Cessna to the Bahamas for “personal time” and returned on a King Air whose owner was not identified in the governor’s records.

Sanford already is facing scrutiny after the AP reported his use of state aircraft for personal and political trips, and charges to taxpayers for more expensive first-class and business-class flights on state business. Attorney General Henry McMaster and legislators have called on the South Carolina Ethics Commission to investigate the state plane use.