Protesters react after police fired tear gas during a rally against a controversial extradition law proposal outside the government headquarters in Hong Kong on June 12, 2019. Dale de la Rey | AFP | Getty Images

Hong Kong activists say they are planning another mass rally at the weekend to pressure the government to drop a plan to allow extraditions to China, as worries over the future of the former British colony's unique status grow. The Civil Human Rights Front, a political advocacy group, announced Thursday on its Facebook page that it applied for a police permit to hold a march on Sunday. That's exactly one week after the group claimed a million people rallied for the Hong Kong government to withdraw the contentious legislation it wants to pass this month. Police estimated the turnout last week was far lower, at about 240,000. But it still marked the largest mass demonstration in the Asian trade and financial hub since 2003, when an estimated 500,000 people gathered in the streets to rally against the government's plans for tighter security legislation.

A bullet was fired into the heart of each citizen ... The people of Hong Kong are pained and infuriated. Civil Human Rights Front

Tensions intensified on Wednesday as clashes between riot police and a large crowd — estimated at more than 10,000 people, according to police — left scores injured in violence outside the local Legislative Council. Police fired tear gas and rubber bullets, while protesters threw objects and charged police lines.

Legal 'loophole'

Lawmakers were scheduled to debate the bill that critics, including foreign businesses, say threatens Hong Kong's protections under a "one country, two systems" framework with China. That has been in place since 1997 when the mainland regained sovereignty from Britain. But the protests made holding the session impossible. While the scale of demonstrations has since subsided, Legco — as the Legislative Council is known — has yet to reschedule the debate. Now, with plans for more protests, concerns are rising again. "I don't know what's going to happen next because the situation, actually, is quite volatile," Audrey Eu, a former Legco member, told CNBC's "Squawk Box" on Friday. The government claims it must act quickly on the bill to plug what it calls a legal "loophole" and extradite a Hong Kong man accused of murder in Taiwan back to the self-governed island. But the change would also allow fugitives to be sent to mainland China, stoking fears the country might use it to go after dissidents and others who speak out against it. Hong Kong's top official, Chief Executive Carrie Lam, has defied protest calls to drop the legislation and step down from her post. She says the government will ensure that no one's human rights are violated as a result of the extradition legislation. The Civil Human Rights Front also said it applied for a permit to gather outside Legco on Monday as part of efforts to stop the bill from passing. "A bullet was fired into the heart of each citizen," it said of the police use of force. "The people of Hong Kong are pained and infuriated."

'Serious damage'