Greta Thunberg is lifted away by police officers after taking part in a new climate action in Oljehamnen, Malmo, Sweden, on Monday. AP

The 20-year-old activist, who has become a key face of the movement to fight climate change, had earlier in the day appeared in court, accused of disrupting traffic and refusing to leave a June protest in port city Malmo.

"It's correct that I was at that place on that day, and it's correct that I received an order that I didn't listen to, but I want to deny the crime," Thunberg told the court when asked about the charge against her. Thunberg said she had acted out of necessity, citing the urgency created by the "climate crisis."

The rally, organised by environmental activist group Reclaim the Future, tried to block the entrance and exit to the Malmo harbour to protest against the use of fossil fuels. "According to me we are in an emergency, and then due to that my action was legitimate," she told reporters after the trial.

Not backing down

After a short trial, the court found her guilty and issued a fine of 1,500 kronor ($144) plus an additional 1,000 kronor to the Swedish fund for victims of crime.

The crime she was convicted of can carry a maximum sentence of six months in prison, but usually these types of charges result in fines.

Asked if she would exercise more caution in the future following her fine, Thunberg said they were "definitely not going to back down." "We know that we cannot save the world by playing by the rules because the laws have to be changed," the activist said.

"It is absurd that the ones acting in line with the science, the ones blocking the fossil fuel industry are the ones having to pay the price for it," she added.

Hours later, Thunberg joined a protest similar to the one in June that resulted in her being fined. Sitting on the road leading to the Malmo port, she put out a sign reading "I block tanker trucks."

Same crime

After about an hour, Thunberg and five others were forcibly removed by police, an AFP photographer at the port reported. "Six people have been removed from the scene," police said in a statement, adding they would be reported for "Disobeying police orders", the same crime Thunberg had just been fined over.

Thunberg shot to global fame after starting her "School Strike for the Climate" in front of Sweden's parliament in Stockholm at the age of 15.

She and a small band of youths founded the Fridays for Future movement, which quickly became a global phenomenon.

Agence France-Presse