WASHINGTON, Oct. 21 (Xinhua) -- The U.S. government supported mortgage enterprises Fannie Mae and Freddie Mac could cost American taxpayers as much as 363 billion U.S. dollars over the next three years, according to a statement released by a federal housing regulator on Thursday.

The two mortgage finance giants are projected to draw 221 billion to 363 billion dollars of government rescue through 2013, more than double the current amount, the Federal Housing Finance Agency (FHFA) said.

To date, the two companies have cost 148 billion dollars from a bailout program of the Treasury Department.

It's the first time that the agency has released a public estimate of the taxpayer tab. The actual amount will depend on whether home prices stabilize or take another dive, the agency added.

"These projections are intended to give policymakers and the public useful snapshots of potential outcomes for the taxpayer support of Fannie Mae and Freddie Mac," said FHFA Acting Director Edward J. DeMarco.

The two companies have been operating under federal control for more than two years after nearly collapsing because of the housing bust.

The U.S. Treasury stepped in to take them over in September 2008, when the rescue was expected to cost a combined 200 billion dollars.

Economists say that the U.S. housing market, which triggered this round of global financial crisis, remains in the wood. (yan)