A strike at Starbucks will expand to over 300 U.S. stores on Tuesday, with more than 5,000 workers expected to walk off the job before the five-day work stoppage ends later on Christmas Eve, the workers' union said.

Earlier, Starbucks said the union “prematurely ended” a bargaining session and called for talks to continue. The coffee chain has said it’s focused on improving workers’ experience and that baristas who work at least 20 hours a week receive $30 an hour, on average, when combining pay and benefits.