The sergeant was arrested by the Met’s directorate of professional standards on Thursday evening, Deputy Assistant Commissioner Andy Valentine said.
“We have been extremely clear we will be unrelenting in our approach to tackling issues at Charing Cross, and anywhere else across the Met”, Mr Valentine said in a statement.
“Internal reporting mechanisms” brought the “fresh matter” to light, he added.
“We continue to encourage and support all our officers and staff to report allegations of criminal conduct and behaviour so we can act swiftly”.