Assistant Director of Housing Poon Kai-tik was among supporters of the Democratic Party's Lau Chin-shek, election expenses reports show.
Mr Poon donated $8,000 to Mr Lau, a candidate for Kowloon West constituency.
He said he was not aware of any rules barring him from making election donations.
'We are both Christians, I've known him for years,' Mr Poon said.
Politics of Hong Kong