Nearly 10,000 people took to the streets in Kuala Lumpur Sunday to protest the opening of Australia-based mining company Lynas’ new rare earth plant.  

The plant, which is the largest outside China, has already received its first shipment of rare earth concentrates and is scheduled to begin operations within the coming weeks, Channel News Asia reported. 

The rally is a culmination of a 13-day march against the plant’s opening, and was organized by environmental activist group Himpunan Hijau, who have been demonstrating against the plant’s opening for two years. 

The activists and demonstrators are concerned with the implications the plant will have on residents’ health, saying that the plant could produce dangerous radiation, the New York Times reported. Lynas has denied such radiation concerns. 

The protesters were in a standoff with police at Kuala Lumpur’s landmark Independent Square, or Dataran Merdeka, vowing to camp there until Monday morning, Xinhua reported. 

“We hope the government can hear his people’s voices. I believe they can’t handle any untoward consequences. Advanced countries like Japan couldn’t handle (radiation-related disasters), let alone Malaysia,” demonstrator Andrew Lim told Xinhua.

Deputy Inspector-General of Police Tan Sri Khalid Abu Bakar told reporters that the protesters had not informed police of their rally, nor received permission to picket in the Square,the Malaysian Insider reported.