COLUMBIA -- Lawyers representing Gov. Mark Sanford asked the state Supreme Court on Wednesday to keep an ethics investigation out of the hands of a Legislature that is deciding whether to start impeachment proceedings this fall.

The Republican two-term governor's travel has been under scrutiny since he returned from a secret June rendezvous in Argentina with a woman he later called his soul mate.

An investigation by The Associated Press showed Sanford used state planes for personal and political purposes and took first-class trips overseas despite state economy travel requirements.

Afterward, the State Ethics Commission started its own probe.

"We asked the court to require the commission to abide by the law and its own regulations by following their procedures and not releasing preliminary materials," Sanford lawyer Kevin Hall said.

The filing said State Ethics Commission Director Herb Hayden "has consistently stated that the commission intends to violate the law and its accompanying regulations" by releasing a preliminary report of its investigation of Sanford.

Hayden told The Associated Press that he has no plans to release anything to the Legislature until it takes steps to impeach Sanford.

Ethics investigations are typically kept secret. But Sanford waived confidentiality after Hayden told him in an Aug. 27 letter that he would only confirm an investigation was under way and release the commission's complaint.

On Sept. 14, Sanford asked the commission to keep its reports confidential until the Ethics Commission makes a decision. But Hayden said that request came only two days before a commission hearing, was premature and there was not enough time for staff to prepare a response.

In a Sept. 15 letter, Cathy Hazelwood, the commission's general counsel, said the request wouldn't be on the agenda because it was "prematurely filed as the investigation is very much ongoing and no report has been begun, let alone completed."

She said Sanford's lawyers would get a chance to argue the issue when the nine-member commission has the findings.

Sanford's lawyers said the court needs to intervene.

"If the Ethics Commission does not abide by the law and impeachment ensues, the public may very well view the process as a kangaroo court in action," Sanford's lawyers said.