A federal judge in Philadelphia has preliminarily rejected a $765 million US settlement of NFL concussion claims, fearing the sum may not be enough to cover injured players.


U.S. District Judge Anita Brody has asked for more financial details from the parties, a week after players' lawyers filed a lengthy payout plan.


Brody, in her ruling Tuesday, notes that the plan is designed to cover nearly 20,000 men for 65 years.


She says she is mostly concerned that not all retired players who are someday diagnosed with a related brain injury will be paid.


The proposed awards would reach $5 million for athletes with amyotrophic lateral sclerosis, or Lou Gehrig's disease; $4 million for a death involving brain trauma; and $3 million for dementia cases.