Three retired New York firefighters who helped clear the wreckage at Ground Zero have all died on the same day from 9/11-related illnesses.

FDNY responders Daniel Heglund, Howard Bischoff and Robert Leaver were all part of the rescue and salvage operations at the World Trade Centre in the aftermath of the al-Qaida attacks on 11 September 2001. They died on Monday.

Childhood friends Leaver, 56, and Bischoff, 58, who had grown up together in New York borough Brooklyn, were both disgnosed with cancers

Leaver was diagnosed with leukaemia in 2003 and retired the next year while Bischoff was diagnosed with colon cancer. Heglund died of esophagal cancer.

"When he was diagnosed, Robert said he was not a victim but a first responder," Leaver's widow, Rosaria, told The New York Post.

In July, it was revealed that more than 2,500 Ground Zero rescuers and responders have been diagnosed with cancer.

The World Trade Center Health Program calculated 1,655 responders had developed cancer, but that figure rose to 2,518 when firefighters and medics were added.

The US government set up the September 11th Victim Compensation Fund for any individual who suffered physical harm or illness, or was killed as a result of the terrorist assault.