The trustee overseeing the liquidation of MF Global has asked for permission to distribute another $685 million to the failed brokerage's customers.

James Giddens filed the request Thursday in the U.S. Bankruptcy Court in New York. Giddens has already returned $3.9 billion to MF Global's U.S. customers, roughly 72 percent of what they claim they're owed.

In his latest request, the trustee asked the court for permission to distribute up to $600 million to customers who traded commodity futures on U.S. exchanges.

Giddens also wants to give $50 million to customers who traded on foreign markets, the first such payment to those trading on foreign exchanges. Another $35 million would be returned to owners of physical property.

If the request is approved, U.S. trading clients would stand to receive more than 80 percent of their claims, according to the court filing.

MF Global, headed by former Goldman Sachs CEO and ex-New Jersey Gov. Jon Corzine, filed for bankruptcy protection on Oct. 31. It was the eighth-largest bankruptcy in U.S. history.

A federal grand jury in Chicago is investigating how $1.6 billion of clients' money went missing at the firm. Regulators are investigating whether it was used to cover MF Global's short-term needs when trading partners lost confidence in the firm and squeezed the brokerage for cash.

That would violate securities laws. Brokerages are required to keep customer money separate from the firm's money.

Much of the missing money belonged to farmers, ranchers and other business owners who bought and sold contracts with MF Global to reduce their risks from the fluctuating prices of corn, wheat and other commodities.