In a quarter in which its revenues are expected to surpass $100 billion for the first time, Amazon says it will spend $500m on a one-time Christmas bonus for its front-line employees.

The pay bump—which will not be paid until January—comes amid plans for strike action over the Black Friday shopping weekend, and growing calls for unionisation.

Dave Clark, the ecommerce group’s head of operations, on Thursday said full-time staff employed in the US from December 1 to December 31 would receive $300. Part-time workers would get $150.