Climate activist Greta Thunberg was detained by police in London after protesting outside an oil and gas conference, preventing some delegates from attending.

Thunberg, who gained fame as a face of young climate activists worldwide, has been detained or removed from protests in Sweden, Norway, and Germany this year.

Video footage captured Thunberg wearing a badge with the slogan ‘Oily Money Out’, calmly speaking to police officers, and later being searched and placed in a police van.

London’s Metropolitan Police have arrested 20 protesters, including activist Thunberg, who locked arms and obstructed entrances to the Intercontinental Hotel. The protesters, who argued that the world is drowning in fossil fuels, were warned before entering the hotel.

Greenpeace reported that hundreds of demonstrators were involved in the protest, preventing delegates from entering.

Two activists scaled the building and unfurled a banner reading ‘Make Big Oil Pay’. Two speakers, Torbjörn Törnqvist, CEO of trading house Gunvor, and Ben Luckock, head of oil trading at Trafigura, missed the event due to the protesters blocking the entrance.