SAN FRANCISCO (AP) – Bankrupt Interstate Bakeries Corp. announced Thursday it will close two San Francisco plants and lay off 650 workers, continuing a cost-cutting spree aimed at saving the endangered maker of Hostess Twinkies and Wonder Bread.

With its latest streamlining measure, the Kansas City, Mo.-based company has announced plans to close six of its 53 bakeries since filing for bankruptcy protection last September. If approved by the bankruptcy court, the purge will jettison 3,800, or 12 percent, of the 32,000 workers who were on Interstate Bakeries payroll.

“In order to ensure a long and successful future for IBC and to save as many jobs as possible the company must continue making these difficult decisions,” said Tony Alvarez II, a turnaround specialist hired to oversee the salvage efforts.

Interstate Bakeries’ prospects for recovery remain murky, partly because Alvarez is still trying to unravel the financial mess that it inherited from the previous management team.

The New York Stock Exchange de-listed the company last year, forcing its shares onto the highly speculative over-the-counter market, where they gained 10 cents to $6.10 Thursday.

The planned San Francisco cutbacks will close a 77-year-old bakery that made Wonder Bread and Twinkies, as well as a 49-year-old plant that produced Parisian bread. Interstate Bakeries also is closing some of its Northern California thrift stores.

The Interstate Bakeries sites previously targeted for closure are in Massachusetts, North Carolina, South Carolina and Florida. On Wednesday, the company said it was cutting 173 jobs at a bakery in Biddeford, Maine, as part of a regional consolidation.

Founded as the Schulze Baking Company 78 years ago, Interstate Bakeries is battling for survival as it struggles to revive its sagging sales amid tougher competition. The company has blamed much of its woes on the country’s growing appetite for low-carbohydrate foods, but analysts say poor management decisions exacerbated the problems.

Since it posted a $27.4 million profit for its fiscal year ending in May 2003, Interstate Bakeries has lost more than $93 million, according to filings with the Securities and Exchange Commission and bankruptcy court.

The company’s deteriorating finances have imperiled its workers’ retirement pensions, which are seriously underfunded, according to SEC documents.

In addition to Wonder Bread and Twinkies, Interstate Bakeries’ other prominent brands include Home Pride, Ding Dongs and HoHos.