Teamsters union truck drivers for Safeway supermarkets went on strike here yesterday after they unanimously rejected a contract proposal that contained wage increases identical to ones that were overwhelmingly accepted by drivers for the Giant Food chain.

A handful of Safeway drivers, all members of Teamsters Local 639, immediately started picketing the chain's main distribution center in Landover, while union leaders said the picketing may be extended to more than 150 stores from southern Pennsylvania to Fredericksburg, Va., by the middle of this week.

The strike had little or no immediate impact on the amount of food in Safeway's stores because the chain delivers almost all of its products to its outlets from Monday to Saturday. Moreover, the union, under a provision of its contract that expired at midnight Saturday, said it will continue to deliver perishable items for 72 hours after posting picket lines, until 1:15 p.m. Wednesday.

Safeway spokesman Ernie Moore said the company expects that customers will find no difference in the quantity of food in its stores because it plans to "operate our truck fleet with management and outside drivers for as long as necessary."

Phillip Feaster, president of Local 639, said four other Teamsters locals with contracts at Safeway have "all sanctioned our strike and . . . pledged to honor our picket line." Officials of the other Safeway locals could not be reached yesterday.

Moore said it was "a possibility" that other union support for Local 639 will hamper Safeway's operations. But he said, "We've got management people ready to go in" to replace unionized warehouse workers if they honor the truckers' picket line. He said nonunion job applicants have been interviewed in the past week for the warehouse jobs and they eventually would replace the management team.

"We are prepared for a long strike," Moore said.

Negotiations between Local 639 and Safeway broke off at 2 a.m. yesterday. No negotiations have been scheduled.

The key strike issue centers on a provision that gives Safeway drivers the right to unload trucks after they make deliveries. Moore said Safeway wants to be able to have drivers of the huge semitrailer delivery trucks drop the trailers at stores for unloading by other workers at Safeway's convenience, as Giant does.

In addition, Moore said, Safeway wants to stock one of its two Fredericksburg stores out of its Richmond distribution center, as it does for a store two miles away.

Feaster said Safeway is trying to service all its Northern Virginia stores out of Richmond, where drivers are unionized but paid about $11 an hour, $3 less than those who work out of Landover.

The Local 639 leader said Safeway, with its demand for new rules on truck unloading, "is trying to divert work that traditionally has been part of our jurisdiction. They're trying to have other unions do our work and cut our base."

Giant's 234 truck drivers represented by Local 639 voted 195 to 2 yesterday to accept a three-year contract that will boost their wages in three stages from $13.87 to $15.57 an hour in the last year of the pact.

The Giant drivers accepted the offer after the chain's management dropped its efforts to impose a two-tier pay system under which newly hired drivers would have been paid substantially less than those who already work for Giant.

"The members were very vocal that they would rather have to give up a pay increase for themselves than have a two-tier system," Feaster said. "We believe strongly that you should get the same pay for the same day's work."

Safeway offered the same $1.70-an-hour wage increase to its 260 truck drivers, garage personnel and truck loaders who are members of Local 639, an increase that would boost their pay over three years from $14 an hour to $15.70. Safeway also dropped its demand for a two-tier pay system.

But the union's leaders recommended that the proposal be rejected because of Safeway's demand for the change in work rules. The rank and file subsequently voted down the package, 199 to 0.

"It is obvious that Local 639 remains insensitive to the competitive situation in the marketplace," Moore said. "The union continues to make demands which place Safeway at a competitive disadvantage vis-a-vis our competition.

"Our drivers are the highest paid in the area," he said. "We did not ask our drivers to take a pay cut. In fact, we offered them the same package as Giant did. We simply asked for parity with Giant, which the union refused to give us. We can no longer condone this labor work rules imbalance."