Buildings Department staff were denied entry into Chief Executive Leung Chun-ying's Stanley flat, which allegedly has an illegal basement, the department said.
The department issued a statement last night on the back of news that Legco president Jasper Tsang Yok-sing will ask Leung to spend more than the 90 minutes scheduled for him on Monday to explain the illegal structures at his Peak homes.
In the statement, the department said its officers, who on Wednesday had tried to inspect the first-floor flat in Block C, Tung Tau Wan Road, were "rejected entry into the residential estate by its management personnel".
In response, Leung said he was unaware of the visit and that the management and his tenants had not informed him about the matter. He said he would co-operate with future inspections.
Leung will attend a 1-1/2-hour session at 5pm on Monday to answer lawmakers' questions on the illegal structures saga and on "subjects of public concern".
But members of the house committee have complained that 90 minutes would not give them enough time.
The Democratic Party's Emily Lau Wai-hing said: "Even pro-establishment lawmaker Chan Yuen-han said the meeting should last for at least three hours."
The Labour Party's Lee Cheuk-yan said: "We are mainly concerned with Leung's personal integrity, but if the session is for 'subjects of public concern', questions about other issues can be mixed into it and there will not be enough time for us."
Meanwhile, Beijing loyalist lawmakers voted down a motion tabled by Lee for a Legco investigation of the government's handling of the illegal structures in Leung's homes. Only 23 pan-democrats supported the move.