Climate activist Greta Thunberg pleaded not guilty to a public order offence charge in a British court on Wednesday, following her arrest last month at a protest in London.

The 20-year-old was detained by police on Oct. 17 after she and dozens of demonstrators locked arms to obstruct the entrances to a hotel where an oil and gas conference was taking place.

Thunberg has become famous as the face of climate activism since she started staging weekly protests in Sweden in 2018, and she now travels around the world addressing crowds at marches and protests. 

She was charged by London police on Oct. 18 and released on bail. If found guilty she could face a fine of up to a maximum of $3,069. 

Before her arrest in Britain, she has this year been detained by police or removed from protests in Sweden, Norway and Germany.