A nine-year-old climate change activist in India was detained by police in New Delhi, according to reports.

Licypriya Kangujam, and fellow activist Aarav Seth, aged 12, were picked up by officers at the weekend after protesting about air pollution outside the Parliament House in the capital. New Delhi has among the worst air quality in the world and the city is often blanketed in thick smog.

Licypriya shared the news that she had been “briefly" held by police on her Twitter account. 

According to a series of posts, she and Aarav were put in the back of a police truck and taken to an “undisclosed location”. They were held for around 40 minutes, according to the protesters. 

“Instead of stopping air pollution, they’re trying to stop me,” Ms Kangujam tweeted.

Licypriya has been a climate activist since she was seven years old and has received a World Children Peace Prize as well as an India Peace Prize. 

Sharing pictures of the poor air quality in the city, she said: "This is not the time to stay silent. I will continue my protest in front of the Parliament House. 21 out of 30 most polluted cities is in India. 

“No concrete action yet. Instead of blame game, we want urgent climate action now with permanent solution to fight the air pollution.”

She also offered to provide a session on air pollution and the climate crisis for New Delhi police officers. 

Indian news site News18 reported that the young activists were not arrested but let off with a warning, and told if they returned to protest outside Parliament House they would be detained. 

The police arrested the children because they had been protesting at a “high-security zone”, according to the network. However Licypriya wrote on Twitter that she held a demonstration at the building each week. 

Indian citizens, fellow activists and scientists shared their outrage at the detention of the young activists. 

Jean-Pascal van Ypersele, a vice-chair with the UN’s Intergovernmental Panel on Climate Change and a climate physicist, tweeted: “Licypriya, who just turned 9 year-old, was arrested on October 18 in India. Her crime? Asking for more climate action! Please support her, listen to her, and follow her! She also has a nice sense of humour... #FaceTheClimateEmergency.”

According to IQAir, a real-time air quality information platform, New Delhi has the worst air pollution of any capital city. Some 1.25 million people are killed by air pollution in India every year.