* Strike affects 10 percent of U.S. refining capapacity
* Most plants operating near normally with non-union labor
* Strike has boosted gasoline futures prices
By Erwin Seba
HOUSTON, Feb 4 (Reuters) - Negotiations will resume onWednesday between Royal Dutch Shell Plc and unionleaders as they haggle over a new wage contract for strikingU.S. refinery workers, the company said.
The two camps have been at an impasse since the UnitedSteelworkers union (USW) called walkouts early on Sunday for thefirst time since 1980 at nine plants with about 10 percent ofU.S. refining capacity, saying Shell left the negotiating tablewhen talks broke down.
Most affected refineries are running near normal, withoperators having called on trained managers, retirees and othersfrom non-union plants to replace workers.
But one plant, Tesoro Corp's 166,000 barrel-per-dayMartinez, California, refinery, was shutting down as part of itwas already undergoing maintenance work, the company has said.
Talks have been difficult as a drop of more than 50 percentin oil prices since June has eroded profits of major companies,prompting executives to say they cannot afford to lift wages forworkers.
The union said talks late on Tuesday made "no progress."Shell called them "productive."
The union has said further walkouts may be ordered at someof the other 63 refineries and chemical plants it represents ifadvances are not made.
"Bargaining continued today, no progress to report, willresume tomorrow," read a text message the union sent to itsmembers.
Shell sounded more positive. "Productive discussion today.Shell and USW agreed to resume talks on Wednesday," companyspokesman Ray Fisher said.
The company has declined to detail the nature of thenegotiations.
Since bargaining first started on Jan. 21, the union hasrejected five offers from Shell.
The union is seeking annual pay increases of 6 percent,double the size of those in the last agreement. It also wantswork that has been given in the past to non-union contractors tostart going to USW members, a tighter policy to preventworkplace fatigue and reductions in members' out-of-pocketpayments for healthcare.
The strikes were the first ordered in 35 years in support ofa nationwide pact that would cover 30,000 workers.
Refiners are promising little or no disruption toproduction, but wholesalers and others have snapped up supplies.
Traders have said the strike contributed to higher pricesfor gasoline futures on Tuesday, though they were down afew cents early on Wednesday at $1.56 a gallon.
Refinery outages can reduce purchases of crude, and U.S. oilprices were down 3 percent at $51.48 after a string ofbig gains. (Additional reporting by Jessica Resnick-Ault; Writing by TerryWade, editing by William Hardy)
