Former immigration chief Laurence Leung Ming-yin was forced to quit when confidence in his integrity was shattered by his handling of a government housing loan and failure to declare his business links. Testifying at a televised Legislative Council hearing, Secretary for Civil Service Lam Woon-kwong disclosed that an Independent Commission Against Corruption probe into Mr Leung's assets found cases that threw grave doubts on the credibility and suitability of keeping him as the chief of immigration. The finding was consistent with a confidential integrity check on Mr Leung completed by the police at the end of June, Mr Lam revealed. Mr Leung was forced to retire on July 5. Mr Lam denied reports that secret data had been leaked by Mr Leung to China. 'There is no evidence, I repeat no evidence, to suggest that the security and integrity of any system for which the immigration service is responsible has been compromised,' he said. Legislators remained unconvinced that the full story had yet been told, with Mr Leung and Chief Secretary Anson Chan Fang On-sang being summoned to testify at a further hearing on Thursday next week. Chairman of the Select Committee Ip Kwok-him said that calling Governor Chris Patten, who is still in London, was just a matter of time. Mr Patten last night denied there had been any cover-up by the Government in the Leung case and said he resented such suggestions. 'We have a civil service of which we can be proud. Any falling of standards could be extremely damaging to Hong Kong,' he said. He said the leaders of the disciplined services had to have the very highest standard and in Mr Leung's case, these were not being met. 'How could we proceed in any other way than in which we did?' Mr Lam said he told Mr Leung on July 5 that the Government intended to require his retirement under Colonial Regulations 59. Mr Lam said if Mr Leung chose not to retire immediately, he was to be given the reasons in a letter. Mr Lam refused to disclose details of the integrity investigations, but said: 'I can only tell the conclusion. Put simply, he failed.' But he did reveal that the unsent letter cited incidents that demonstrated Mr Leung's failure to meet the 'high standard of conduct' required for the head of a disciplined service. He said Mr Leung had failed to comply with civil service rules that required him to repay a $1.76 million government housing loan immediately after a Canadian flat he bought with the money was sold. Mr Lam said Mr Leung had failed to make full disclosure of investments in a company called Dragon House Investment, which is partly owned by legislator Lau Wong-fat, one of the biggest landowners in the New Territories. An investment of $100,000 by Mr Leung in New Hong Kong China Advertisement Ltd 'with a view to develop advertising business in China' also went unreported, said Mr Lam. Mr Lam said the late repayment of the loan was a 'serious breach of regulations' and that in his senior position Mr Leung should have understood that failure to comply with the assets declaration requirement might result in disciplinary action including dismissal and compulsory retirement. He said: 'He chose to hide [the details] . . . As head of the Civil Service Branch, I'm greatly disappointed with him. Personally, I'm disgusted with this behaviour. 'If he has no guilty conscience, he did not have to choose to retire.' Challenged on his insistence that Mr Leung retired for 'personal reasons', Mr Lam admitted that in his first appearance at the inquiry he had chosen 'technical' and 'narrow' interpretations of the phrase. 'If members and the public felt they were misled, I deeply regret that and feel sorry.' Mr Leung later thanked the Government for rejecting allegations against him in the British press. 'I'm happy that the Government has shown my innocence in this respect.' THE ALLEGATIONS Leung failed to report selling a flat in Canada, bought with a $1.76m government loan, and did not repay it until five years after the sale; He failed to disclose full details of his investments; He failed to disclose ties with legislator Lau Wong-fat in one investment; He failed to disclose a $100,000 investment in a China-based business, which might not have been permitted, even if he had applied.