SACRAMENTO (AP) - Gov. Arnold Schwarzenegger's administration pledged to fight any attempt to ease protections for old coastal redwoods that could be threatened by a timber company's bankruptcy filing.

Pacific Lumber Co., a subsidiary of Houston-based Maxxam Corp., sought bankruptcy protection in Texas earlier this month, saying it could no longer make a profit because of logging restrictions on its 200,000 acres of timberlands in Humboldt County.

The Scotia-based company blamed state water regulations, separate from the logging rules it agreed to in 1999 as part of a "habitat conservation plan" to protect endangered species.

Pacific Lumber accepted the 50-year conservation plan as part of an agreement to sell 7,400 acres of old-growth redwoods to the state and federal governments for $480 million. That land is now the Headwaters Forest Reserve.

Mike Chrisman, secretary of the state Resources Agency, said the state will fight any legal effort to end or amend the habitat plan.

"We intend to be dogged and unyielding in our efforts to protect California's interests and hold (Pacific Lumber) to all of its obligations," Chrisman said Friday in a letter to Senate President Pro Tem Don Perata, D-Oakland.

Pacific Lumber spokeswoman Andrea Arnot said the company has not asked the bankruptcy court to change the Headwaters agreement. She wouldn't speculate if the company will make such a request.

Former state Sen. Byron Sher, D-Palo Alto, said the redwoods agreement was attached to the deeds of Pacific Lumber's land to make sure that any new owners would be bound to the same rules.

"Anyone who owns these 200,000 acres would be subject to it," Sher said.

Sierra Club spokesman Paul Mason welcomed the administration's pledge.

"Taxpayers made a significant investment in these environmental protections," Mason said, "so it's very welcome to see the state will be taking all possible steps to ensure those commitments are honored."