Freddie Mac expects to see credit losses of $10 billion to $12 billion on the book of mortgages it currently owns, the mortgage finance company's chief executive said on Tuesday.

We would expect that our total future credit losses on our current book of business would total approximately between $10 billion and $12 billion, Chief Executive Officer Richard Syron told an investors conference sponsored by Goldman Sachs.

Freddie Mac has already recorded many of those losses from recently failing loans and had previously disclosed its expectation of multi-billion dollar write-offs, said analyst Jim Vogel, who tracks the companies for FTN Financial in Memphis, Tennessee.

The 10 to 12 billion dollar headline number was as disclosed on November 20 and 'about half' that number (was) reflected in a previous statement, Vogel said in a note to clients.

Syron said he has a gloomy outlook for the housing market because the worst still lies ahead, and he sees a 10 percent decline in national home prices between the peak of the recent housing frenzy to its eventual bottom.

If I were you, I would want in this time period someone running one of these companies (Fannie Mae and Freddie Mac) to err on the side of pessimism rather than optimism, he said.

Fannie Mae and Freddie Mac are the nation's two largest sources of mortgage finance, and they are government-chartered companies with a mission to promote home ownership.

In the coming months, Syron said, the public will increasingly see the distressing public face of massive foreclosures and that could imperil the entire economy.

We have seen a ton of foreclosures but we have not seen a lot of pictures of people standing in front of their house with their furniture on the front lawn saying 'What am I going to do? he said.

As that starts to happen, and it will happen, I am afraid of the impact that this has, he said, citing a risk that a public concern over the housing market could curtail consumer spending.

Household wealth in housing is about $21 trillion. It does not take a big shift in consumer confidence, in consumers worrying about things, for it to have an effect on the economy. I think it will get worse before it gets better, he said.

(Reporting by Patrick Rucker; Editing by Chizu Nomiyama)