A federal judge said Friday that he will not approve a proposed $657 million settlement for people sickened after working on the World Trade Center site until it is negotiated further.

U.S. District Judge Alvin Hellerstein said that legal fees must be lowered and paid by an insurance fund set up by the city; individual plaintiffs must be given a proposed dollar amount before being asked to opt in or out of the proposal; and Hellerstein himself must supervise how plaintiffs' claims are categorized.

The category of illnesses the 10,000 workers claim to have suffered would affect the payout. Hellerstein's remarks came after 10 plaintiffs offered a variety of views at the settlement hearing. The judge had moved the proceeding to a larger courtroom than the one he usually uses to accommodate the many lawyers and plaintiffs involved.

- CNN's Hussein Saddique in New York contributed to this report.