THE power of the ICAC Commissioner has been challenged by Legislative Councillors and legal experts following the sacking of the body's most senior local officer. Alex Tsui Ka-kit, the ICAC's deputy director of operations, was dismissed last week by Commissioner Bertrand de Speville. Under the Independent Commission Against Corruption (ICAC) Ordinance, the Commissioner can sack any member of staff without explanation. Human rights expert Johannes Chan Man-man, a senior law lecturer at Hong Kong University, said an independent review board should be set up to check the power of the Commissioner and allay fears of abuses. He said the board should be responsible for dealing with decisions made by the ICAC. Anyone who was aggrieved by a decision could appeal for a revision of his or her case. ''The power given to the ICAC Commissioner is so great that it could easily be abused, especially in such a closed and secretive system,'' he said. However, Mr Chan added: ''I don't think, in Tsui's case, giving reasons for his dismissal would be a good thing.'' With checks and balances in place, decisions made by the ICAC would appear more legitimate, Mr Chan said. The United Democrat's spokesman on security matters, James To Kun-sun, backed Mr Chan's suggestion and said a monitoring body should be formed to look at the performance of the graft-fighting body. Mr To said the idea had been widely mooted in the monitoring of some sensitive Government organisations overseas, but he added that further consideration must be given as to who should belong to the monitoring body. He was concerned by the fact that the Commissioner was directly appointed and was responsible only to the Governor. This might allow manipulation under a future government. Mr To said: ''We base our trust on the Governor, who then directs the power of investigation to the ICAC Commissioner. I am not trying to cast doubt on the integrity of any of them, but this could bring chaotic results in extreme circumstances.'' The deputy chairman of Legco's security panel, Simon Ip Sik-on, said there was a need to review the power delegated to the Commissioner. He said the power under section 8(2) of the Ordinance had been formulated in 1979 - when the graft-fighting body was first set up - and it was outdated. ''With the reasons supplied, he [a sacked employee] could at least seek an appeal through the proper legal channel,'' Mr Ip said. Pro-China legislator Tam Yiu-chung agreed the power of the ICAC Commissioner should be checked. He suggested requiring the Commissioner to get the consent of the Governor-in-Council before exercising the power of dismissal.