Authorities in the Chinese capital have issued a ban on low-altitude flights and drones over the city ahead of a five-yearly congress of the ruling Chinese Communist Party (CCP) next month.

The CCP will hold its 20th National Congress from Oct. 16, amid a mounting wave of censorship and curbs on the freedom of dissidents, petitioners and rights activists around the country.

Light and ultra-light aircraft, gliders, delta wings, hot air balloons, airships, para-gliders, drones, model aircraft and free and tethered balloons are banned from Beijing's skies through Oct. 31, the municipal police department said in a notice dated Sept. 15.

"It is prohibited for units, organizations or individuals to fly low, slow or small aircraft such as drones ... for any purpose," the statement said.

"Violations will be ... punished by police according to [current laws]," it said, reminding the city's residents that flying lanterns are already banned.

Meanwhile, outspoken critics of the government have been informed they are to leave Beijing under police escort in the next few days, with similar measures reported in Tianjin, Hunan and Jiangxi provinces.

"I'm traveling right now," Beijing-based commentator and former 1989 student protester Ji Feng told RFA on Wednesday. "[Officials] from my hometown are here with me."

"My friends are all being taken away from their homes [on enforced 'vacation'] at the moment," he said. "Some left earlier than me ... I'm coming back at the end of October."

"I'll be allowed home as soon as the congress is over." Daily forcible disappearances

Ji estimated that thousands of other activists around China are also being ordered to leave town ahead of the event.

Shenzhen-based dissident Lin Zhengliang said the security measures appear stricter than in previous years ahead of similar politically sensitive events.

"This is unprecedented," Lin said. "The current controls on dissidents at designated locations is kind of crazy."

"Dissidents are being forcibly disappeared every day, including those who are taken out of town on 'vacation'," Lin said. "They also hold people on criminal detention and release them on bail pending trial, extended the control period beyond the 20th National Congress."

"Even in Jiujiang city, Jiangxi province, which is far from the political center, Beijing, there are many dissidents who have gone missing and have finally been confirmed as in detention," Lin said.

Authorities in the capital have already begun expelling petitioners -- ordinary Chinese who pursue complaints about official wrongdoing through the "letters and visits" system -- from Beijing.

"My landlord suddenly told me I had to [go back to my hometown]," a petitioner currently living in Beijing's Daxing district who gave only the surname Li told RFA.

"They are driving us away to maintain stability because the 20th National Congress is about to start," she said.

Migrant workers are also being targeted, she said.

"My husband started working at the garbage dump here in Daxing yesterday, and just two days later, he was fired," Li said. "[The policy of] 'registering' the floating population means that you're not allowed to stay in Beijing."

"You are not allowed to work here, and you are not allowed to live here," she said.

'Stability maintenance'

A resident surnamed Wang, who lives on the outskirts of Beijing, said state security police have been conducting mass raids on migrant populations in the area.

"The state security police are detaining people every day, and holding them in various places," Wang said. "Yesterday, they forcibly held down and dragged away someone from Yancheng, Jiangsu province."

"Anyone with petitioning materials on them will be forced to leave Beijing, as if they were escorting prisoners," she said.

Authorities in one local community in the southwestern province of Sichuan are tightening "stability maintenance" measures by appointing local heads of household security supervisors for every 10 households, reports said.

Each supervisor under the Neijiang Chang'an community neighborhood committee will be responsible for anyone deemed a risk to social stability in their group of 10 households.

A dissident who gave only the surnamed Tan from the central province of Hunan said additional stability measures were put in place in his hometown of Zhuzhou city from Wednesday.

"Yes, full controls are in place starting today," Tan told RFA. "A local friend of mine said he has been taken out of town."

Petitioners in the northern port city of Tianjin said the authorities have set up three levels of checkpoints to catch petitioners trying to get into Beijing that way.