The head of an officers' union who claims his integrity has been questioned yesterday challenged the police chief to prove him a liar. In a move that could sour relations between management and rank-and-file police officers, Tony Liu Kit-ming, chairman of the 1,800-member Local Inspectors' Association, has written to the force's bosses requesting a hearing to clear his name. At issue are comments Police Commissioner Tsang Yam-pui made to a Legislative Council committee meeting on Friday about a move to cut the pay of officers suspended from work while under investigation. Mr Tsang told the meeting Mr Liu was aware the force had sought legal advice over the move. Mr Liu was informed by deputy police commissioner Dick Lee Ming-kwai on Wednesday, Mr Tsang said. Mr Liu disputes this version of events. He says he first heard about the legal advice on Friday. In a letter sent to management yesterday, Mr Liu wrote: 'I take the words of the Commissioner of Police as openly accusing me of being a liar, which throws doubt on my integrity. This is not a trivial matter as integrity is of paramount importance for a police officer.' He requested an urgent and full investigation. 'I am ready to accept any serious punishment if I am proven a liar,' he wrote. Mr Tsang insisted last night he was not questioning the integrity of Mr Liu, but stood his ground on the facts. The legal advice prompted Mr Tsang to support a change to the long-standing practice of giving full pay to suspended officers. Under the Police Force Ordinance, the commissioner may cut the pay of officers below the rank of superintendent by up to half when they are suspended. Mr Liu said he asked the management in December if it had sought legal advice to check whether the commissioner's discretionary power to cut officers' pay was contrary to natural justice. But he said he received no reply. He told legislators he was not aware of the legal advice until the moment Mr Tsang mentioned it in the Public Accounts Committee meeting on Friday. But Mr Tsang told legislators Mr Liu knew. The heads of two other officers' groups - the Junior Police Officers' Association and the Overseas Inspectors' Associate - which attended the meeting, supported him. Mr Lee said last night: 'I have told them that we have sought advice from the Department of Justice which says the Police Force Ordinance is not against natural justice. 'I can accept if he says he has not seen the legal advice, but I cannot accept it if he says he has not been told about it. We have told them on various occasions verbally that we've sought legal advice which said the Police Force Ordinance was sound. But he [Mr Liu] said he could not accept it.' Mr Liu said: 'I'm very disappointed. Mr Tsang has rocked the foundation of mutual trust we have been building over the past many years.' Mr Tsang rejected suggestions the pay row would create a rift with rank-and-file officers. 'We have differences on this issue. These differences could be ironed out, not with just one person, but with the different officers' associations,' he said. 'We'll need to explain and communicate with them more to let them understand more about the impact of the change. But in fact the change would not be great.' Mr Lee declined to comment on Mr Liu's request for a disciplinary investigation as he had not seen his letter.