The number of cancer-stricken New York Police Department (NYPD) employees who worked at Ground Zero after the 9/11 terror attacks is eight percent higher than originally thought.

The revelation comes from city data that Mayor Michael Bloomberg's administration refused to reveal for several years.

Of nearly 40,000 NYPD officers and civilians who worked at Ground Zero and related sites after the 9/11 attacks, 321 reported having cancer to the police force's medical division or applied for disability benefits, an increase from the 297 cases documented by the officers' union.

All attribute their failing health to inhaling the toxic dust.

Mayor Bloomberg gave the numbers Friday night to Public Advocate Bill de Blasio -- a likely 2013 mayoral candidate who has taken charge of this issue -- and the Mount Sinai School of Medicine, New York, which is treating ailing first responders.

Mount Sinai just completed a study showing cancer rates went up 14 percent among the workers.

De Blasio slammed the city for failing to release the names of those with cancer.