Environmental activist Greta Thunberg has been arrested at a pro-Palestinian protest in Copenhagen against the Israel-Hamas war, according to a spokesperson for the student group organising the demonstration.

Danish police detained six people including Thunberg on Wednesday at the University of Copenhagen after 20 people blocked the entrance to a building and three entered, a police spokesperson said.

While the police did not confirm the identities of those detained a representative from the Students Against the Occupation said Thunberg, 21, was one of those arrested.

And news outlets Ekstra Bladet published a photo of Greta Thunberg, showing her in handcuffs and wearing a black-and-white keffiyeh shawl over her shoulders.

Thunberg has also shared photos on Instagram of riot police entering a building where Students against the Occupation was holding a protest.

A Copenhagen police spokesperson said: “I can’t confirm the names of those arrested, but six people have been arrested in connection with the demonstration. They are suspected of forcing their way into the building and blocking the entrance.”

Recently Thunberg was arrested in Malmo, Sweden for protesting against Israel’s participation in the Eurovision contest in the city. Demonstrators held signs accusing Israel of “committing genocide” in the Gaza strip and claimed that "Eurovision celebrates genocide."

Students against the Occupation said in a statement posted on Instagram that “while the situation in Palestine only gets worse, the University of Copenhagen continues cooperation with academic institutions in Israel”.

“We are occupying [the university’s] central administration with one demand: academic boycott now.”

Since last spring pro-Palestinian protests have set up encampments across universities around the US and Europe.