Four scheduled operations at Mater Dei Hospital on July 6 had to be put off because not enough nurses were prepared to work overtime.
Health Minister Joseph Cassar explained in reply to a parliamentary question that the patients were on the Urology list of operations and three had already been admitted to hospital.
Because of the shortage of nurses, there was no fixed list of nurses for these operations and nurses were asked to work overtime.
He said that efforts had continued up to the last minute to bring in enough nurses, but this proved unsuccessful.