Prison officers united yesterday to launch a lawsuit against the Government, claiming thousands of hours in unpaid overtime. The officers are suing the Commissioner of Correctional Services and the Secretary for Civil Service for an hourly rate of 1/140th of their monthly salaries. The writ filed in the High Court by eight CSD officers, representing 3,625 colleagues, claims they have been deprived of overtime allowances which they are entitled to under the Civil Service Regulations. It says the officers, some of whom have retired, were required to perform 'overnight on-call' duties, which confined them to barracks. 'The plaintiffs are entitled to be paid an hourly rate of 1/140th of their respective monthly salaries for all the overnight on call duties they performed, less all the special allowances they each received, if any,' the writ says. The number of hours claimed by each officer ranges from 30 to many thousands. 'Despite repeated demands and requests, the defendant has failed, refused or neglected to pay any of the plaintiffs their respective overtime allowances,' the document says. In a court battle against the department last October, retired CSD officer Shau Lin-chi won payment for about 200 extra night shifts. The Government could face an overtime claim of up to $2 billion from thousands of CSD officers who were working under similar conditions as Mr Shau.