Officials say that they are unable to conduct further investigations into claims that 56 mainland over-stayers received humiliating treatment at Victoria Prison last month. In a letter to the legislature, the Commissioner for Correctional Services said: 'We have made preliminary inquiries but are unable to undertake further investigations in the absence of detailed accounts.' The allegations included strip searches, forced agreements to return to the mainland, verbal abuse, the use of handcuffs and denial of access to telephones. The mainlanders were released on their own recognisance on April 1, pending their case going to the Court of Appeal. Members were told that no one had made a formal complaint despite the authorities' appeals. In a separate reply, the Immigration Department said its officers had not abused their powers during another group of over-stayers' term at the Ma Tau Kok Detention Centre.