(Updates with Shell statement, USW message)
By Erwin Seba
HOUSTON, Feb 5 (Reuters) - Union leaders rejected a sixthcontract offer Royal Dutch Shell Plc made to U.S.refinery workers, and a pause in negotiations was calledThursday on the fifth day of a strike, though talks are set toresume next week.
The United Steelworkers union (USW), which representsworkers at 63 U.S. refineries, had recommended that localsreject the proposal, which was floated after the first bigwalkouts since 1980.
"The parties have recessed and have agreed to resume talks,"Ray Fisher, spokesman for Shell whose U.S. unit leadsnegotiations for oil companies, said after the union rejection.
About 4,000 workers at nine plants, including sevenrefineries accounting for 10 percent of U.S. refining capacity,have been on picket lines since Sunday in California, Kentuckyand Texas.
The walkouts are in support of a nationwide pact that wouldcover 30,000 workers. Companies have called in trained non-unionworkers to keep plants running almost as normal.
"The USW has rejected the sixth offer from Shell," a unionofficial said. The union also said talks were in recess, pendingan information request.
In a message to members late on Thursday that was seen bythe news media, the union said talks would resume next week.
"Industry offer shows minimal movement," the message read.
The union is seeking a tighter policy to prevent workplacefatigue, which is tied to accidents. It also wants annual payincreases of 6 percent, double the size of those in the lastagreement, and work that has been given in the past to non-unioncontractors to start going to USW members. Reductions inmembers' out-of-pocket payments for healthcare are also sought.
The two camps have been in a stalemate since the USW calledthe strikes, saying Shell had left the negotiating table whentalks broke down on Saturday. Picket lines went up shortly aftermidnight on Sunday.
Negotiations have been tougher than in years past. A drop ofmore than 50 percent in oil prices since June has eroded profitsat major oil companies, prompting executives to say they cannotafford to lift wages for workers.
The USW may order further walkouts at some of the otherrefineries and chemical plants it represents if there is noprogress in the talks, the union has said.
On Wednesday, two refineries affected by the strike - TesoroCorp's Los Angeles-area refinery in Carson, California,and Marathon Petroleum Corp's Galveston Bay Refinery inTexas City, Texas - reported leaks to regulators.
Strikes could complicate the ability of the companies tocarry out maintenance work after the upsets, analysts say. (Writing by Terry Wade; Alden Bentley and David Gregorio;Editing by Ken Wills)