MIAMI - Republican South Carolina Governor Mark Sanford, a conservative seen as a presidential contender before a sex scandal wrecked his reputation, faces 37 possible ethics violations, the state ethics commission said on Monday.

The commission said it had determined there was probable cause to support allegations that Sanford used taxpayer money to fly business class when he should have been in coach, used state planes for personal travel and campaign funds for personal expenses.

A committee of South Carolina lawmakers was expected to begin formal work this week on a measure to impeach Sanford, who has rebuffed repeated calls for his resignation. The resolution could be put before the state House of Representatives in January.

Sanford, at one time a rising star in the Republican Party, saw his fortunes tumble when he admitted in June that he had an affair with an Argentine businesswoman. He is married.

The ethics commission said it would schedule a hearing to investigate 37 allegations that Sanford used his office for personal financial gain. Most of the allegations were unrelated to the affair.

Eighteen of the counts allege that he authorized first or business class flights for himself to or from Tokyo, Beijing, London, Sao Paulo and other cities when he should have flown coach.

Nine counts allege that he used state planes for personal trips, including one from North Myrtle Beach to the state capital of Columbia about 140 miles away to get a haircut and another to attend a son's sporting event.

He also made trips to attend a book signing and a birthday party for a campaign contributor, the ethics commission said.

Sanford admitted to his affair a week after a mysterious disappearance, when his staff said he was hiking the Appalachian Trail. He later said he had flown to Argentina to visit his lover.

The admissions prompted an investigation into whether he had misused public funds for the trip. He was cleared.

His wife, Jenny, and their four sons moved out of the governor's residence in August.

Sanford was a prominent opponent of President Barack Obama's economic stimulus bill that sought to boost the recession-hit U.S. economy. He rejected $700 million of stimulus funds for his state.

(Reporting by Jim Loney, editing by Jane Sutton and Frances Kerry)