New development chief Paul Chan Mo-po is at the centre of an investigation by buildings officials just days after taking office over claims that he and his wife illegally subdivided properties.
The couple also face claims that they understated the selling price of another flat to avoid tax.
Chan - who took over after Mak Chai-kwong was arrested by the Independent Commission Against Corruption and quit less than two weeks into the new government's term of office - said the flats were owned by his wife, Frieda Hui Po-ming.
Hui said she had quit as a director of the holding company which owned the flats and that they were now managed by her family. Chan, whose responsibilities include supervising the Buildings Department and tackling subdivided flats - which have been linked to a series of fatal fires in recent months - said the investigators would not report to him and would treat the case in an impartial manner. Reports emerged on Monday that Chan and Hui had been directors of a company, Harvest Charm Development, which owned two flats in Kowloon that were divided into three to five units each.
While Chan quit his directorship in 1997, documents obtained by the Post show that Hui resigned on July 1 - the date Chief Executive Leung Chun-ying's government took office.
Chan, then a lawmaker, had been tipped to join Leung's administration in the new post of deputy financial secretary before the Development Bureau vacancy arose.