By Michael Bristow
BBC News, Beijing
China has launched a crackdown on political dissidents and potential troublemakers ahead of the Communist Party's 17th congress, which begins next month.
The spiritual movement Falun Gong was banned in China in 1999
The congress, held every five years, is the party's most important public political event.
At this year's gathering, which will be held mostly behind closed doors, Chinese President Hu Jintao is expected to tighten his grip on power, and the authorities are keen that those with other ideas are kept well away.
Public Security Minister Zhou Yongkang, a member of the party's politburo, identified a wide range of "hostile forces" that will be targeted.
"All police should...strike hard on overseas and domestic hostile forces, ethnic splittists, religious extremists, violent terrorists and the Falun Gong cult so as to safeguard national security and social stability," he said.
Falun Gong is a spiritual movement that was banned in China after staging a massive demonstration in central Beijing in 1999.
Mr Zhou also referred to political dissidents, campaigners and people who advocate independence for the western regions of Xinjiang and Tibet.
The crackdowns are to prevent disruption at the party congress
He said efforts should also be made to step up control of the internet to create what he described as a "harmonious online environment".
China already tries to prevent ordinary citizens logging on to certain websites.
News outlets are also being targeted in the run-up to the congress, which will be attended by more than 2,000 party delegates.
One editor of a Chinese newspaper told the BBC that the party's central publicity department had issued two notices to editors telling them what stories they could and could not print.
The first notice was sent in July, and the second in mid-August.
"They told us there should be no negative reports before the party congress. We shouldn't report stories about things such as land rights, petitioners and major incidents, such as accidents," he said.
In what is perhaps an indication of just how worried newspaper editors are about making mistakes in the run-up to the congress, five of them recently managed to publish almost identical front pages.
There were striking similarities between the headlines, the placement of photographs and the articles selected for print.
Cleaning up the streets
The authorities are also trying to clear Beijing's streets of potential annoyances before the congress.
A settlement for petitioners - ordinary people who travel to Beijing to petition the central government about local injustices - could be demolished next week.
Up to 4,000 petitioners are believed to live in the "village", in the capital's Fengtai District. That number often increases when important political meetings are being held.
Control of the internet will be stepped up, ministers say
"Petitioners are some of China's most vulnerable citizens, and they have the right to housing while they pursue their legal claims," says Sophie Richardson, of US-based Human Rights Watch.
Notices have gone up in the settlement that residents have to leave the area before noon on 19 September.
Although the authorities say the area needs to be cleared to make way for road construction, the rights group says the timing suggests it is also about cleaning up the city before the party congress.
There is also a month-long crackdown in Beijing on beauty parlours, which are often fronts for prostitutes or gambling dens.
And the state-run China Daily reported that property owners are being told not to lease their homes to people who have "irregular lifestyles".
The party congress is China's main set-piece political event that will endorse future policies and the next generation of leaders.
To ensure it goes off smoothly, party leaders are leaving as little as possible to chance.