Washington  - David Moffett, the chief executive of Freddie Mac, resigned Monday after only six months at the helm of the nationalized mortgage lender, which suffered billions of dollars in losses as the US housing market collapsed.

The government-chartered lender said it was Moffett's own decision and not the result of pressure from President Barack Obama's administration. Moffett will exit and an interim head will be appointed by March 13, the company said.

Freddie Mac and its larger sister-lender Fannie Mae own or guarantee about half of all US mortgages. The US housing sector has suffered a price collapse that led a record number of homeowners to face foreclosure - the chief cause of a massive financial crisis that has plunged the US into recession.

The two firms were placed in a conservatorship in September - the first in a series of dramatic government interventions in the ailing financial sector - after reporting collective writedowns of more than 14 billion dollars in mortgage-related assets.

Moffett was chosen by the government to lead Freddie Mac at the time. James Lockhart, head of the Federal Housing Finance Agency that regulates Fannie and Freddie, said the government was working to ensure a "smooth transition" away from Moffett.

The US Treasury has promised up to 400 billion dollars in government guarantees to the companies in the hopes of keeping lending to homeowners alive. dpa