Auckland councillor Cameron Brewer wants a council review into Len Brown's affair with Bevan Chuang widened to investigate a trip the mayor made to Hong Kong.
Mr Brown has not officially declared the trip in January this year, sparking criticism from Mr Brewer and in right-wing circles.
The mayor travelled alone on the Hong Kong Government-funded "special visitors programme" trip to look at infrastructure projects and governance issues.
Bevan Chuang, the Hong Kong Chinese woman he had a two-year affair with, told the Herald she did not accompany him and was in New Zealand at the time.