Activists formed a human chain to protest Black Friday sales at a shopping mall in the La Defense business district west of Paris, France. (AFP)

Climate activists staged protests across Europe on Friday to denounce the environmental toll of mass consumption, while shoppers hit the streets and the internet as retailers of all stripes touted pre-holiday bargains.

The American “Black Friday” tradition of a post-Thanksgiving day of deals has taken hold in Europe as a long weekend of sales, alarming critics who say it encourages unbridled and wasteful spending.

This year, activists have targeted the climate costs of frenzied shopping, in particular from delivering the millions of items ordered from Amazon and other online retailers.

French NGOs had pledged a “Black Day for Amazon,” with protesters blocking a distribution center outside Paris on Thursday, and others near Lyon and Lille on Friday.

The Extinction Rebellion campaign group posted on Twitter images of protesters being forcibly removed by police from the Lyon site.

“Amazon today emits as much greenhouse gases as a country,” Jean-Francois Julliard, head of Greenpeace France, said at a sit-in at Amazon’s headquarters just north of Paris on Friday.

Meanwhile, young activists formed a human chain to prevent shoppers from reaching stores at the shopping mall in La Defense, the business district west of Paris.

Similar human chains were formed in the central city of Saint-Etienne and town of Roanne.

But many retailers across France nonetheless reported brisk Black Friday business amid drizzling rain.

A salesman at the Holland Bikes store in the Villiers neighborhood said an early rush of clients snapped up several bikes at 20 percent off.

In Germany, hundreds of Amazon workers walked off the job to escalate their long-running fight for better pay and working conditions.

The strike called by the powerful Verdi union is set to last until Tuesday morning and will also cover “Cyber Monday”, another extravaganza of online discounts in what is a crucial sales period for Amazon.

“Their work cannot be had at rock-bottom prices,” Verdi said in a statement, demanding a collective labor agreement to ensure “a living wage and good, healthy jobs”.

In the Netherlands, Students for Climate called for a human chain in Maastricht.

Others urged people to halt purchases altogether to protest the US-inspired event, such as the “Buy Nowt Friday” in Bradford, northern England, organised by artists and anti-poverty advocates.

But many British retailers hoped deep discounts would bolster sales that have suffered from the uncertainties linked to Brexit.

In Madrid, where stores across the city are offering Black Friday deals, Greenpeace held a rally just days ahead of the opening of the COP25 conference on fighting climate change.

Activists unfurled a banner on the facade of a building on the Gran Via, a major shopping artery in the Spanish capital, which read “Consumerism = Climate Crisis.