Hundreds of thousands of people took to the streets in Hong Kong on Sunday, protesting a government plan that would allow extraditions to mainland China. Rising fears over the erosion of Chinese civil liberties have driven the semiautonomous city apart from Bejing. The mass demonstration – one of the largest in Hong Kong’s history – was the latest evidence of those fears.

The bill would allow Hong Kong to detain and transfer people wanted in countries with which it has no formal extradition agreements. The claim from Carrie Lam, Hong Kong chief executive, is that the new law is urgently needed to prosecute a Hong Kong man who is wanted in Taiwan for murder. But critics fear that the bill will allow virtually anyone to be detained in mainland China, where the Communist Party is known for targeting political activists.

Riot police responded to the protesters using pepper spray and water cannons. The protesters had gathered around the legislature to stop lawmakers from debating a plan.

“Hong Kong is a civilized city, but they don’t listen to the citizens,” said Grace Tsang, 25. While the demonstrations have delayed the process, they are unlikely to prevent the law from being enacted. Pro-Bejing lawmakers hold 43 of the legislature’s 70 seats.