BEIJING — When imprisoned Chinese dissident Liu Xiaobo received the Nobel Peace Prize last month, some human rights activists and political observers hoped that the award would spark a national debate about change in the country’s authoritarian government.

So far, the Chinese Communist Party’s response has been to harass, arrest or confine dozens of dissidents to their homes.

Liu’s wife, Liu Xia, was put under house arrest immediately after the Oct. 8 Nobel announcement, and has been silent the past two weeks. Fellow dissident Yu Jie, a good friend of Liu’s, said police had placed a table in front of his door and kept three men posted at all hours to keep him from leaving.

Another man, Guo Xianliang, reportedly was arrested in the southern city of Guangzhou on Oct. 28 and held under suspicion of trying to subvert the state after he handed out leaflets about Liu Xiaobo and his life’s work.

“They said Liu Xiaobo is a criminal and we should not spread information about criminals,” said Wu Wei, a friend of Guo who was later questioned by police.

Like Liu Xiaobo, Wu is a member of the Independent Chinese PEN Center, a chapter of the free-speech advocacy PEN organization. Since Liu’s award, Chinese security forces have questioned or detained at least 20 of the group’s members, according to organizers.

The crackdown has shown the lengths to which the Chinese government will go to weed out what it perceives as threats to its rule. Those who’ve been hauled into police stations or put under guard have no following among the general public, and only a very small circle of activists and state security even know their names.

Even Liu Xiaobo, still serving an 11-year sentence for “inciting subversion of state power,” isn’t a household name in Beijing, much less the country, even after his Nobel recognition. The political manifesto he helped draft, which called for free speech and a more open political system, has been blocked from distribution in China.

Still, police have methodically rounded up those associated with Liu or political activism, especially in the capital.

Some observers have speculated that the government wants to head off public displays of support for Liu on Dec. 10, the date of the Nobel Prize ceremony, but there’s no way of knowing its aim, because there’s been no public acknowledgement of the detentions.

After initially saying nothing about Liu and the Nobel, Chinese state media have run a series of editorials and articles accusing him of being a criminal and an attention-hungry agent of the West.

“As the West’s tool, Liu will be abandoned by the Chinese people,” a column in China Daily concluded.

“The biggest threat to this government is freedom of speech. They don’t like Liu’s ideas about being able to criticize the government,” said Li Fangping, a prominent human rights lawyer in Beijing who for about a week after Liu’s award was allowed to travel only with a police escort.

Another human rights advocate, Beijing lawyer Pu Zhiqiang, is still under police surveillance after being held in a small hotel for three days. He posted an online account of his interrogation by Beijing police officials, which included one of them calling Pu a “running dog for the Western countries” and a “traitor to your motherland” in an obscenity-laced tirade.

In a phone interview, Pu said the ordeal suggested that officials “are scared of people knowing about Liu Xiaobo.”

Speaking from his home Friday, Yu said he had no idea what the future would bring. In August, Yu published a book that sharply criticized Prime Minister Wen Jiabao, who’s popular with most Chinese and has called for political reform.

If nothing else, Yu said, his experience has made it clear to him that Wen’s talk of a more democratic nation was hollow.

“The government has chosen to react (to Liu’s award) in the worst way. It’s shown its uglier side. … This shows China is not a country under the rule of law,” he said.