The settlement was announced Thursday evening by the WTC Captive Insurance Co., a special entity established to indemnify the city and its contractors against potential legal action as they moved to clean up the site after the Sept. 11, 2001, terror attacks.

The deal, which still must be approved by a judge and the workers themselves, would make the city and other companies represented by the insurer liable for a minimum of $575 million, with more money available to the sick if certain conditions are met.

Most if not all of the money would come out of a $1 billion grant from the Federal Emergency Management Agency.

Mayor Michael Bloomberg called the settlement "a fair and reasonable resolution to a complex set of circumstances."

"The resolution of the World Trade Center litigation will allow the first responders and workers to be compensated for injuries suffered following their work at Ground Zero," Bloomberg said in a statement.

Workers who wish to participate in the settlement would need to prove they had been at the World Trade Center site or other facilities that handled debris. They also would have to turn over medical records and provide other information aimed at weeding out fraudulent or dubious claims.

For the settlement to be enforced, 95% of the workers would need to agree to be bound by its terms.

The agreement comes with just two months to go until the first trials are to begin in the case. Thousands of police officers, firefighters and construction workers who put in time at the 16-acre site in lower Manhattan had filed lawsuits against the city, claiming it sent them to ground zero without proper protective equipment.

Many of those workers now claim to have fallen ill. A majority complained of a respiratory problem similar to asthma, but the suits also sought damages for hundreds of other types of ailments, including cancer.