The amount of outstanding Fannie Mae buyback requests at Bank of America (BAC) continues to pile up.

The bank faces more than $3 billion in Fannie Mae mortgage buyback requests aged at least 120 days as of March 31, triple the amount from three months prior, according to a financial filing from the GSE Wednesday.

Fannie and BofA severed some business ties in February when the two disagreed over outstanding claims. BofA can still deliver some refinance and Home Affordable Refinance Program loans to the GSE.

The bank claimed a new policy Fannie undertook to request buybacks based on mortgage insurance rescissions was not valid under a repurchase claims settlement worth $3 billion that was signed more than a year ago. The bank felt it conflicted with the settlement and told Fannie it didn't intend to make any repurchases under the new guidelines.

The more than $3 billion in outstanding claims represents 71% of the Fannie Mae aged claims. It dwarfs the $1.7 billion of outstanding requests at JPMorgan Chase (JPM), the next largest backlog, according to the filing.

"We're still unresolved," said Fannie Mae Chief Financial Officer Susan McFarland in an interview, adding BofA continues to make some payments on some of the $7 billion in total repurchase requests from Fannie.

A BofA spokesman said there were no new developments in the talks.

Fannie reported enough profit in the first quarter to avoid drawing bailouts from the Treasury Department. Fannie has not changed its estimate for what it might claw back from its total repurchase requests as a result of BofA. But the GSE said in its filing if the negotiations worsen, taxpayers could be on the hook.

"If we collect less than the amount we expect from Bank of America, we may be required to seek additional funds from Treasury under our senior preferred stock purchase agreement," according to the filing.