(Recasts with USW making counterproposal)
HOUSTON, Feb 12 (Reuters) - The largest U.S. refinery strike since 1980 entered its 12th day on Thursday with no talks scheduled until next week and industry representatives were weighing a union counterproposal, said a labor spokeswoman.
No details were provided about the counterpropasal by the United Steelworkers union (USW) or when it was passed to lead U.S. refiner negotiator Shell Oil Co, said USW spokeswoman Lynne Hancock.
"The USW is waiting to receive the information it requested from Shell and for Shell to respond to the USW's counterproposal," Hancock said.
Shell told the union on Wednesday it would need a week to compile a response to answer an extensive information request from the USW about the use of non-union contractors in refineries. Talks are scheduled to resume on Wednesday, Feb. 18
The USW has said that non-union workers hired by companies contracted to do regular refinery maintenance are less qualified than union workers.
Also on Thursday, Tesoro Corp Chief Financial Officer Steven Sterin told analysts during an earnings conference call that production at the company's 166,000-barrel-per-day (bpd) refinery in Martinez, California, will remain shut down until the strike ends.
Two of Tesoro's California refineries and another in Washington are among nine refineries where workers are on strike, affecting 13 percent of U.S. capacity. A chemical plant and power co-generation plant have also seen walkouts.
Tesoro is operating the Martinez refinery near San Francisco as a terminal.
Tesoro Chief Executive Greg Goff said during the call that it was too early to discuss hiring permanent replacements for the striking workers.
Shell Oil Co, the U.S. arm of Royal Dutch Shell Plc , said it remained in contact with the USW.
"The lines of communication between the USW and Shell remain open," Shell spokesman Ray Fisher said.
Since the talks started on Jan. 21, sticking points have included the use of non-union contractors and how to monitor worker fatigue. Wage increases and health benefits are also on the bargaining table.
The USW is seeking a three-year, industry-wide pact that would cover 30,000 workers at 63 U.S. refineries that together account for two-thirds of domestic capacity.
Over the weekend, walkouts widened to include BP Plc's Whiting, Indiana, refinery and its joint-venture refinery with Husky Energy in Toledo, Ohio.
Companies have called on trained temporary replacement workers to keep their plants running at nearly normal levels.
Refineries where the strikes are taking place have reported malfunctions since walkouts began on Feb. 1.
A 70,000-bpd gasoline-producing fluid catalytic cracking unit was shut earlier this week at Shell's 327,000-bpd refinery in the Houston suburb of Deer Park, Texas. (Reporting by Erwin Seba and Kristen Hays; Editing by Paul Simao, Bernard Orr)