Tens of thousands of Hong Kong residents took to the streets of the former British colony to push for greater democracy in a rally fuelled by anger over Beijing's recent warning that it holds ultimate authority over the southern Chinese financial center.
Organisers said they expected the crowd to swell to least 180,000 for Tuesday's march to press for reforms allowing residents to elect their leader. Other reports put the rally turnout at half a million.
The march came after an informal poll on democratic reform drew an unexpectedly high turnout of nearly 800,000 votes, but was branded "illegal and invalid" by Beijing.
July 1 is traditionally a day of protest in Hong Kong and also marks the anniversary of the handover from Britain to China in 1997, under a "one country, two systems" agreement.
That agreement gives residents civil liberties not seen on the mainland, including free speech and the right to protest.
But there are heightened fears that those freedoms are being eroded.