Greta Thunberg and a group of activists were held yesterday during rallies against the destruction of the German coal hamlet of Luetzerath, according to the police.

A representative for the regional police division stated that it was unclear what would happen to Thunberg (20), who joined demonstrators at the site last week to oppose the development of the RWE-owned mine.

Last weekend, riot police and bulldozers removed demonstrators from buildings in the village, leaving only a few in trees and an underground tunnel. Still, protesters, including Thunberg, remained at the site conducting a sit-in until Tuesday.

Thunberg was arrested while demonstrating at the Garzweiler 2 open-pit coal mine, approximately 9 kilometres from Luetzerath, where she sat with a group of demonstrators near the mine's edge.

A Reuters witness saw Thunberg sitting alone in a large police bus after she was seized.

Reuters camera reveals that a police officer told the group, "We will use force to bring you to the identity check, so please cooperate."

"Greta Thunberg was among the campaigners who ran towards the cliff. However, she was halted and transported out of the immediate danger zone with the others to establish their identities, a police representative for Aachen told Reuters, adding that one protester had leapt into the mine.

The spokeswoman stated it was unclear what would happen to Thunberg or the group she was detained with or whether the activist who plunged into the mine was hurt.

Thunberg was dragged away by three police officers and held by one arm at a location further from the mine's edge than where she had been seated with the others.

The woman was then led back to the police vans.

The Swedish climate activist addressed the 6,000 protestors who marched towards Lutzerath on Saturday, calling the mine's expansion a "betrayal of present and future generations."

She stated, "Germany is one of the world's largest polluters and must be held accountable."