Buildings officers found an unauthorised space of 320 square feet behind a wall at Chief Executive Leung Chun-ying's house hours after Executive Council convenor Lam Woon-kwong urged him to explain further a possible cover-up of the illegal extension.
The director of buildings, Au Choi-kai, meanwhile, broke his silence to defend his department against accusations that it had shielded Leung by hiding facts.
Building officers who went to Leung's house at No 4 Peel Rise on The Peak last night said they had found a space of 320 sq ft behind a wall that inspectors had earlier noted as suspicious. They gave no further details.
The space was 120 sq ft larger than Leung had described in a statement last Friday that he released in an effort to cool the controversy over illegal structures at his two houses. He has yet to say whether he will agree to lawmakers' demands that he answer their questions in person.
Lam said: "The public still thinks he has not explained clearly. The chief executive should consider prudently at least clearly responding to the questions against his integrity once and for all. Otherwise, his authority to govern will be damaged."
But Lam asked the public not to jump too soon to the conclusion that the chief executive had an integrity problem.
Since Leung released a 14-page statement last week, he has been asked why he did not disclose during the chef executive election campaign his discovery and sealing of the extension that was opened by inspectors yesterday.
Leung's statement listed all the illegal structures at No 4 and No 5 Peel Rise, including the extension, which he said measured 200 sq ft.
The Buildings Department was accused of concealing information to protect Leung because it did not mention the suspicious wall in response to media inquiries in June, before Leung took office. It was also asked why it did not make a follow-up inspection until this month.
Au, defending his department, told journalists waiting outside at his offices in Ho Man Tin: "It had never happened that we have favoured the owner, nor had we stopped investigations because of pressure exerted from the senior management."
He said the department did not disclose the "problematic" wall to the media because it did not know what was behind it. It was usual practice not to disclose details of an unfinished investigation. Asked why the department did not ask the owner to open up the wall earlier, Au said it showed no immediate danger and officers would usually allow an owner time to provide information for further investigation.
Au's statement triggered more criticism as not all media were informed, except those waiting outside his office.
The department's spokeswoman said the "ad-hoc" arrangement was made because the gathering of reporters outside the department could affect its operation. She said that a transcript would be issued.
A meeting of the Legco house committee today is expected to confirm that a no-confidence motion against Leung will be raised by Democratic Party lawmaker Wu Chi-wai in the legislature on December 12.
Leung supporter Lew Mon-hung, a delegate to the Chinese People's Political Consultative Conference, said he was disappointed with Leung's mishandling of the incident because he had "said too much".