The speaker of Singapore's parliament resigned after admitting to an extramarital affair, adding to a list of scandals that have undermined the city-state's reputation for clean and efficient governance.

Michael Palmer, the speaker and a member of Singapore's ruling People's Action Party, said his conduct was "improper" and a "serious error of judgment," according to reports by the strait-laced island's state media.

The woman Palmer had an affair with was employed by a government statutory board and worked in Palmer's constituency.