Hong Kong police have arrested the organisers of the biggest pro-democracy rally since the city was handed back to China, sparking outrage from campaigners who denounced the arrests as "political suppression".

Five members of the Civil Human Rights Front, including its convener, were arrested on Friday three days after the march, which the group said mobilised half a million people to voice anger at Beijing's ever-tightening grip on Hong Kong.

"They are making arrests even though we have had such a peaceful procession," the group's convener Johnson Yeung said after two of his colleagues were picked from their homes on Friday morning.

This is about political suppression.

Johnson Yeung, democracy activist

"This isn't about any one reason, this is about political suppression," he said before surrendering to police with two others from the group.

Police did not immediately comment on the arrests.

But the group's vice convener, Icarus Wong, told AFP that they were arrested on frivolous charges including "obstruction of police duties" during the largely peaceful rally.

Police hauled activists, many lying on the ground with their arms chained to each other, onto coaches that took them to a temporary detention centre. All protesters have since been released.

Discontent in Hong Kong is at its highest level in years over Beijing's insistence that it vet candidates before a vote in 2017 for the city's next leader.

Pro-democracy group Occupy Central has said it will stage a mass sit-in later this year unless authorities come up with acceptable electoral reforms.

Hong Kong enjoys 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.

Meanwhile, China's top newspaper on Friday dismissed fears that the autonomy of the former British colony was being eroded, saying Beijing's policy had not and would not change, following the rally.

In a front page commentary the People's Daily, the official newspaper of the ruling Communist Party, said the white paper was proof that China was committed to Hong Kong's high degree of autonomy.

"Some people think that the white paper deviated from the basic policy the centre [of the party] first proposed, and others worry about whether the centre will squeeze Hong Kong's high degree of autonomy," it wrote."This is all totally baseless."

Source: Agencies