By Lisa Baertlein

LOS ANGELES The head of the union representing 340,000 United Parcel Service workers on Friday said he's ready to keep talking with the company, even though his bargaining committee rejected its "last and final" contract offer.

Negotiations between the Teamsters and UPS deadlocked last week, with the world's biggest package delivery company saying it had no more to give and the Teamsters demanding better pay for workers who missed out on labor shortage-driven pay increases during the COVID-19 pandemic.

The contract covering UPS workers who sort, load and deliver packages expires on July 31.

"The clock is on our side not theirs. I assume at some point they'll be reaching out looking to try and get a deal," Sean O'Brien, general president of the International Brotherhood of Teamsters, told Reuters following a worker rally in New York.

Earlier in the day, UPS said it remained focused on reaching an agreement before the current one expires. At the same time, it said it would begin training non-union employees to deliver packages in the event of a strike.

UPS delivers about 20 million packages a day - roughly a quarter of U.S. parcel volume. A stoppage could delay shipments of everything from Amazon.com orders to critical medicines, and fuel inflation-stoking supply-chain disruptions. One estimate put the economic impact of a 10-day strike at more than $7 billion - one of the costliest in at least a century.

The stakes are high for both sides.

UPS, which aims to hold down labor costs to compete with non-union rivals, could lose customers in a strike, while the Teamsters count UPS as the largest employer of Teamster-represented U.S. workers.

UPS posted significant profits during the pandemic and rewarded executives and shareholders, O'Brien said. "Everyone has gotten a piece of the pie except for the people that actually touch the packages and provide the goods and services," he said.

(Reporting by Lisa Baertlein in Los Angeles; editing by John Stonestreet)