Beijing (AsiaNews/Agencies) - China has intensified its crackdown on petitioners and dissidents ahead of a key party meeting starting on Thursday, with protestors and human rights groups reporting brutal beatings by police.

In the weeks ahead of the Communist Party's Central Committee plenum, police have rounded up thousands of petitioners who came to Beijing to air their grievances.

Many activists said the frequency of the arrests and the level of brutality in detention was unprecedented. "The arrests are getting more frequent and are fiercer than ever," Wang Jinlan, 41, from central Henan province said. "The government is behind this violence. Without its backing, how could law enforcement officers dare be so brutal?"

People in a squatter area in southern Beijing known as "petition village" said they had witnessed many others like themselves being beaten and dragged away by police.

One activist from the northeastern province of Heilongjiang, who gave his name as Li, said he would try to protest on Tiananmen Square during the meeting, of 198 Central Committee members and few hundred other guests, to make his voice heard. "I'll go to Tiananmen Square, if I'm not arrested by then," the 34-year-old said. "I've been imprisoned so many times already, what am I afraid of now? I'm a loyal follower of Chairman Mao, I will insist on telling the truth."

Li has been petitioning authorities for more than 10 years over an unjust court verdict on a violent dispute which resulted in him spending three years in a "re-education through labour" camp - the de-facto prison in China.

Petitioners from all over China - many of whom have suffered injustice at the hands of corrupt officials - have for years headed to Beijing before major national events to try and make their voices heard.

New York-based Human Rights in China last week said some 36,000 people have been rounded up since early September.  It said many were brutally beaten and herded into a gymnasium in an apparent move to ensure public order before the party meeting. Police and the government have refused to comment.

Many petitioners said they had been put in police custody several times during past political events and most had suffered injuries from beatings.

Wang said she was locked in a cage with around 10 other people last March during a meeting of the National Party Congress, China's parliament. "We were treated like animals, we had no food, no drinks and no access to the toilets - it was so insulting," she said.

"The government talks about human rights all the time, but we have no human rights whatsoever."

Du Mingrong, 52, said she was still suffering from injury pains after numerous beatings, once with an electric baton.

"Are they treating us like this because our pleas are embarrassing them?" she said, adding that she was once threatened with being sent to a lunatic asylum.

At the squatter area, by a railway track, those petitioners not yet rounded up live in squalid conditions, in crumbling brick-huts or makeshift tents near a rubbish tip.

Jin Rongzheng, whose home in Zhejiang province was forcibly demolished with his wife nearly killed inside, said he would continue to plead with authorities until they heard his case.

"If your complaint reaches [Premier] Wen Jiabao then you have a hope, otherwise there is no hope at all," he said.

Meanwhile, surveillance on some dissidents has been stepped up, with Shanghai-based Li Guotao arrested and several other Beijing-based activists closely watched.

A relative of severe acute respiratory syndrome (Sars) whistleblower Jiang Yanyong said he remained under constant surveillance since his release in July after a near two-month detention for his public criticism of the 1989 Tiananmen Square massacre.

Meanwhile, the telephone line of an ousted Party Central Committee member, Bao Tong, was repeatedly cut off this week, while Jiang Qisheng, who was imprisoned for writing essays commemorating the 1989 events, said plain clothes officers had been watching his every move.