Images on daily Ekstrabladet showed the 21-year-old climate activist, wearing a black-and-white keffiyeh shawl draped over her shoulders, being escorted out of a campus building by police.

Thunberg meanwhile shared images on Instagram of riot police entering a building where the group "Students Against the Occupation" were staging a protest.

"I can't confirm the names of those arrested, but six people have been arrested in connection with the demonstration," a Copenhagen police spokesman told AFP.

"They are suspected of forcing their way into the building and blocking the entrance," he said.

The 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."

Pro-Palestinian protesters have set up encampments at universities around the United States and Europe since last spring to protest Israel's war on Gaza and its occupation of Palestinian territories.

The 11-month Israeli assault has killed at least 40,819 people in Gaza, according to the territory's health ministry. The UN rights office says most of the dead are women and children.

*This story was edited by Ahram Online.