WASHINGTON — Federal National Mortgage Association again has asked taxpayers for more money after reporting a first-quarter loss of more than $13 billion.

The mortgage finance company, which was rescued by the government in September 2008, said it needs an additional $8.4 billion from the government to help cover mounting losses.

Federal National Mortgage Association says it lost $13.1 billion, or $2.29 per share, in the January-March period. That takes into account $1.5 billion in dividends paid to the Treasury Department. It compares with a loss of $23.2 billion, or $4.09 a share, in the year-ago period.

The rescue of Federal National Mortgage Association and sister company Federal Home Loan Mortgage Corp. is turning out to be one of the most expensive aftereffects of the financial meltdown. The new request for aid will bring Federal National Mortgage Association's total to $83.6 billion. The total bill for the duo will now be nearly $145 billion.

Late last year, the Obama administration pledged to cover unlimited losses through 2012 for Freddie and Fannie, lifting an earlier cap of $400 billion.

Fannie and Freddie play a vital role in the mortgage market by buying mortgages from lenders and selling them to investors. Together the pair own or guarantee almost 31 million home loans worth about $5.5 trillion. That's about half of all mortgages.