Former New York police officers and firefighters are among 106 people accused of being involved in a huge fraud linked to the September 11 attacks in the city.

The accused allegedly collected tens of thousands of dollars a year in social security benefits by claiming they were incapacitated by serious psychiatric disorders and other ailments.

But, according to court documents, they were continuing to live their normal lives.

One of the accused flew a helicopter and another played blackjack in Las Vegas. Another taught and performed mixed martial arts while claiming benefits of between $30,000 and $50,000 a year.

Of the accused, 80 were retired police officers or firefighters.

"Many participants cynically manufactured claims of mental illness as a result of September 11, dishonouring the first responders who did serve their city at the expense of their own health and safety," Manhattan district attorney Cyrus Vance Jr said in a statement.

As far back as 1988, the four main defendants - Raymond Lavallee, 83, Thomas Hale, 89, Joseph Esposito, 64, and John Minerva, 61 - conspired to help or make hundreds of applicants falsely claim disabilities in order to collect benefit payments in addition to their public pensions, the indictment and court documents showed.

Prosecutors said the applicants claimed they suffered from a psychiatric condition that prevented them from working, such as post-traumatic stress disorder (PTSD), anxiety or depression.

"This alleged scam further depleted the already limited resources available for battling the real and complex conditions of PTSD and depression," Mr Vance said.

Applicants 'coached to falsely describe depression' symptoms

New York City Police Department (NYPD) Commissioner William Bratton said: "The retired members of the NYPD indicted in this case have disgraced all first responders who perished during the search and rescue efforts on September 11, 2001, and those who subsequently died from 9/11 related illness, by exploiting their involvements that tragic day for personal gain."

Hale and Esposito, the latter a retired member of the NYPD, allegedly coached benefit applicants to falsely describe symptoms of depression and anxiety to doctors they had recruited.

They instructed applicants on how to fail memory tests with plausibility, how to dress, and on their demeanour.

For example, almost every claim included phrases such as "I nap on and off during the day" and "I have the TV on to keep me company".

Edward Ryan, a special agent at the US Social Security Administration, said: "The crimes alleged in this indictment outline a highly organised, far-reaching criminal enterprise that targeted the Social Security Disability Insurance program."

"These individuals allegedly relied on lies, deceit, and under-the-table payments while they bilked the Social Security Trust Funds of tens of millions of dollars and, in many instances, exploited the tragic events of September 11, 2001 for their own gain.

"This exploitation, combined with the fact that many of those indicted formerly held positions of public trust, make these crimes all the more egregious."

More than 2,700 people were killed in New York on September 11, 2001, when two airplanes hijacked by Islamic militants slammed into the World Trade Center.

AFP