Climate activists are blockading Amazon warehouses across the U.K. on Friday in an attempt to pressure the ecommerce giant on one of its busiest days of the year to improve working conditions and end business practices that hurt the environment.

Members of Extinction Rebellion targeted 13 Amazon fulfilment centers in the United Kingdom with the aim of disrupting 50% of the company’s deliveries on Black Friday, which marks the unofficial start to the holiday shopping season.

Activists blocked the entrance to Amazon’s warehouse in Tilbury, just east of London, with an effigy of Amazon founder Jeff Bezos sitting on top of a rocket.

At Amazon’s distribution center in Dunfermline, Scotland, about 20 Extinction Rebellion members strung banners across the entrance road that said “Make Amazon Pay” and locked themselves together, stopping trucks from entering and some from leaving.

The group is demanding Amazon provide better working conditions, clear environmental commitments, and for the company to pay its fair share of tax.

“The action is intended to draw attention to Amazon’s exploitative and environmentally destructive business practices, disregard for workers’ rights in the name of company profits, as well as the wastefulness of Black Friday,” the group said.

Extinction Rebellion said it was part of a wider international effort that’s also targeting Amazon fulfilment centres in the U.S., Germany and the Netherlands.

Amazon did not directly address the protests in response to a request for comment, but said the company takes its responsibilities “very seriously.”

“That includes our commitment to be net zero carbon by 2040 — 10 years ahead of the Paris Agreement — providing excellent pay and benefits in a safe and modern work environment, and supporting the tens of thousands of British small businesses who sell on our store,” the company said.

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