Former boy band promoter Lou Pearlman will have to repay victims of his decades-long investment fraud at least $300 million in restitution.

A federal judge on Wednesday asked lawyers to draw up the order for his approval.

It's unclear whether the creator of the Backstreet Boys and 'N Sync will be able to raise those funds while behind bars. He's serving a 25-year sentence on federal fraud charges.

Prosecutors also wanted U.S District Judge G. Kendall Sharpe to tack on interest, making the repayment $424 million.

Pearlman's defense says that's unfair because the money was never invested. The judge said he'd make a decision after Pearlman returns at least some of the principal.

So far investigators have recovered few assets remaining from Pearlman's former entertainment empire.