Police on Friday arrested the organisers of Hong Kong's biggest pro-democracy rally since the city was handed back to China, sparking outrage from campaigners who denounced the "political suppression".

Five members of the Civil Human Rights Front, including its convener, were arrested 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 isn't about any one reason, this is about political suppression," he told reporters before surrendering to police with two others from the group.

The five, including three women, were arrested for "not complying with police instructions" and "obstructing police officers from performing their duties" during the July 1 rally, said a police statement released late Friday.

"During the July 1 rally, the organisers' truck leading the procession was proceeding very slowly, they did not heed the advice and warnings of the officers present," the statement said.

"They used loudspeakers to incite other protesters to stop and block the road," it added.

But the organisers have denounced the charges as frivolous.

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.

A Hong Kong lawmaker on Thursday hurled a glass of water at Leung Chun-ying, expressing anger over his perceived silence on the July 1 rally, television footage showed.

The glass missed Leung as he brushed off criticism from pro-democracy lawmakers, who later walked out of the legislative assembly.

"Leung Chun-ying does not want to respond after more than 500,000 people took to the streets but instead he is taking these actions to show he wants to suppress organisers of rallies to make us afraid," Yeung said.

Security officials arrested 511 protesters at a sit-in early Wednesday following the July 1 rally for illegal assembly or obstructing police.

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.

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.

Pastor of state church 'sentenced to 12 years' in China
Beijing (AFP) July 04, 2014 - A pastor of a state-sanctioned church in China has been sentenced to 12 years in prison, his lawyer and an overseas rights group said Friday, accusing authorities of "fabricated charges".

Zhang Shaojie was detained with about 20 other members of the Nanle County Christian Church in the central Henan province last November.

"Nanle District People's Court sentenced pastor Zhang to 12 years in prison for fraud and gathering crowds to disturb public order," his lawyer Yang Xingquan told AFP on Friday.

The public order offence referred to by the lawyer is commonly used when authorities want to silence dissent.

Zhang was reported to have been involved in a land dispute with local authorities, but details remain unclear.

Corrupt local officials often seize land which they then sell to developers, a major source of anger across China.

The US-based religious rights group China Aid Association said previously that in addition to Zhang, at least 20 other members of the Protestant church had been detained.

"Total fabricated charges," Bob Fu, president of the group, said on Twitter Friday, in a message confirming the sentencing.

Calls by AFP to Nanle District People's Court went unanswered Friday.

Communist authorities have frequently clashed with members of unofficial, or "house", churches, with demolitions of houses of worship and beatings of parishioners not unknown.

But it is unusual for authorities to crack down on a state-sanctioned church such as Zhang's, which is part of China's government-run National Three-Self Patriotic Movement, the official name for the approved Protestant church.

The Chinese government estimates that there are more than 23 million Christians in the country, with most concentrated in the prosperous and densely populated areas along the eastern coast and Yangtze River.