Henry Tang said it was unfair for Leung Chun-ying to attack him over unauthorized building work in his home during the election campaign when he knew he had the same problem.
"It was unfair for him to criticize me when he also had illegal structures [in his Peak residence]," Tang said.
He recalled his former rival's remarks that Leung was merely negligent in his handling of the illegal structures at his home, and that he did not deliberately hide the truth.
"If this is negligence, I hope there will not be any negligence in governance in the future," he said.
The former chief secretary also revealed he may seek approval today to build a brick wall to seal off the illegal basement at his Kowloon Tong house - just as the chief executive has done at his Peak home.
Tang said so far the Buildings Department has not approved his applications to demolish the basement.
He said building inspectors have used all sorts of equipment, including high-tech drilling devices, to collect concrete samples from the basement.
"All decorations have been demolished now [in the basement]," Tang said.
"What I know is that the illegal structures have almost been demolished [by officials]."