Bangkok's governor, who is seeking re-election in two months, is facing criminal charges over his extension of a contract to operate the city's elevated mass transit system.

The charges filed Wednesday by the Department of Special Investigation make Gov. Sukhumbhand Paribatra the city's second chief executive in four years to face legal action.

Sukhumbhand's term was to expire Friday, but he resigned early to clear the way for new polls in 60 days. He is accused of lacking the authority to extend the contract for Bangkok's "Sky Train" transit system.

His predecessor Apirak Kosayodhin was accused of malfeasance in connection with the purchase of firefighting equipment. That case is still pending. Both are members of the Democrat Party and deny any wrongdoing.

The Democrats are Thailand's main opposition party.