The trustee supervising the liquidation of MF Global Holdings' brokerage has said that there is a shortfall of at least $1.6 billion to pay commodity customers' claims.

James Giddens, the trustee, gave the estimate after counting allowable customer claims and the assets under his control. Giddens, who previously estimated the shortfall at about $1.2 billion, said that an additional $400 million is missing from customer accounts.

The gap was calculated after counting about $6.9 billion in claims by commodity customers, said Giddens spokesman Kent Jarrell.

Giddens based the revised estimate in part on information gathered from claims forms that commodity customers recently filed. The forms show that about 40 percent of commodities customers hail from five states, including Illinois and New York, where the firm had dual headquarters, the trustee said in a statement.

Giddens has estimated a total of $6.9 billion in claims of which $3.9 billion has already been paid back. He has kept another $1.4 billion in reserve for now, which is yielding the estimated $1.6 billion gap.

The gap between MF Global's securities customers' claims and assets available for them hasn't been calculated yet, and all claims will have to be checked for accuracy, according to statement from Giddens. Also, there could be possibilities of duplicate claims as well as claims those will be disallowed, which could bring down the final estimate.

Customers who traded in the U.S. have received about 70 percent of their cash back. But customers who traded overseas have yet to receive any money.

MF Global Holdings Ltd, the parent of the brokerage, filed for bankruptcy Oct. 31 in the middle of fears about its exposure to risky European debt.