Thanksgiving might only be celebrated in the U.S. — but Black Friday is becoming a major event around the world. It's historically been a day when hoards of U.S. shoppers, on the day after Thanksgiving, rush into stores offering huge discounts to kick off the holiday shopping season. It's an event that puts retailers "in the black." Now international retailers are increasingly using the Friday after Thanksgiving as an opportunity to lure in deal-hungry shoppers around the world. Inside an Amazon distribution center in Tilbury, to the east of London in the U.K., shelves are stocked with everything from water filters to the newest Lego board game in preparation for a busy weekend of sales. As of mid-morning Friday, Amazon said it had seen customers in the U.K. shopping at "record levels" with 100,000 toys and 60,000 beauty items already being purchased since midnight. "We're certainly prepared for one of our busiest days," Jonatan Gal, regional operations director at Amazon in the U.K., told CNBC.

Robots operate at the Tilbury Amazon fulfillment center in the U.K. on Black Friday. CNBC

Amazon hired 20,000 seasonal workers across the U.K. for this year's holiday period. Gal said the company prepares all year long to ensure operations run smoothly when the shopping season kicks off. "We know our customer wants to get the product faster and faster," he said. A recent report from research firm eMarketer found consumers in the U.K. and in Nordic countries are some of the most avid Black Friday buyers. "While there are signs that the Black Friday frenzy may be beginning to subside in the U.S., interest in the shopping holiday is growing across most of Europe," the report said. The ease of online shopping means customers don't need a day off to take advantage of discounts. An October report from consultancy PwC found British shoppers will spend an average of £234 ($300) between Black Friday and Cyber Monday. An estimated 45 percent of shoppers will make purchases on their laptops or desktop computers, while 26 percent will buy in stores.

Black Friday and Cyber Monday sales are also taking off in France, as consumers start to embrace discounts outside of the traditional legally-designated summer and winter sales periods. Adobe estimates 48 percent of French consumers will do their holiday shopping during Cyber weekend this year. The craze has also spread to the rest of Europe including major markets Italy, Spain and Germany. In Asia, countries like Japan and India are also starting to see discounted shopping deals during this period from retailers like Amazon. But some campaigners have also used the shopping holiday to protest at what they see as inhumane working conditions at Amazon distribution centers. The GMB Union in the U.K. planned several protests around the country on Friday, suggesting hundreds could demonstrate at warehouses in Rugeley, Swansea, Peterborough, Milton Keynes and Warrington. Action was also expected in Spain and Italy. A statement from Amazon U.K. said the claims of unsafe working conditions were wrong. "According to the U.K. Government's Health and Safety Executive, Amazon has over 40 percent fewer injuries on average than other transportation and warehousing companies in the U.K.," the company said. "We encourage everyone to compare our pay, benefits and working conditions to others and come see for yourself on one of the public tours we offer every day at our centers across the U.K."