Ai Weiwei, one of China’s most prominent artists and an outspoken critic of the communist regime, was taken from Beijing’s airport by security agents Sunday as he was about to board a flight to Hong Kong. Police later raided his studio.

Ai is the most high-profile activist to have been detained in a government crackdown in which dozens of bloggers, human rights lawyers and writers have been swept up.

The arrests seem related to the government’s concern that activists in China want to launch a “jasmine revolution” similar to the popular uprisings roiling autocratic governments in the Middle East and North Africa.

Some of those detained have been accused of “inciting subversion of state power,” a catch-all term used to jail anyone critical of Communist Party rule. Liu Xiaobo, the 2010 Nobel Peace Prize winner, faced the same charge and received an 11-year prison sentence.

Since mid-February, when anonymous calls for “jasmine rallies” in China began circulating on the Internet, 26 people have been arrested, 30 have disappeared and are presumed held by security forces, and 200 have been placed under “soft detention,” meaning their movements are restricted, according to a count by the group Chinese Human Rights Defenders on Thursday.

But the arrest of Ai and the others appeared to mark what human rights groups and others called a new and more sinister phase in China’s ongoing, and typically cyclical, repression of dissidents. In the past, such sweeps of activists have preceded major events on the calendar — the 2008 Olympics, major Communist Party meetings or the Nobel Prize ceremony in Oslo last December — and have receded once the event ended.

The arrests of bloggers and writers, in particular, on subversion charges suggests a rollback of the limited open space recently allowed for free opinion on the Internet and particularly on popular Twitter-like microblogging sites.

“This is not a crackdown in the classic cycle of tightening and loosening,” said Nicholas Bequelin, Hong-Kong based China researcher for Human Rights Watch. “This is an effort by the government to redraw the lines of permissible expression in China, to restrict the most outspoken advocates of global values.”

Activists such as Ai — an active Twitter user — have been continually pushing the boundaries of what is allowed, while increased connectivity is giving ordinary Chinese people more access to uncensored information and viewpoints.

Chinese Human Rights Defenders, in its Thursday statement, said, “In the context of the democratic uprisings taking place in the Middle East and North Africa, the Chinese government, fearful of its own people, is counting on getting away with staging one of the most repressive campaigns in more than a decade because of the international community’s preoccupation with events elsewhere.”

The outspoken Ai, 53, was the artistic director for the “Bird’s Nest” Olympic Stadium, but he later turned critical of the Games. He has been arrested before: In 2009, in the western city of Chengdu, Ai was beaten so badly that he required surgery to have blood drained from his brain. Late last year, he was stopped at Beijing’s airport from flying to South Korea because authorities feared he might go to Oslo to attend the Nobel ceremony for Liu. Liu is in prison, and his wife, Liu Xia, is under house arrest.

Ai was prevented from having a solo exhibition of his work at a Beijing gallery this year, and in January authorities demolished his newly built Shanghai studio. In March, Ai announced that he was opening a studio in Berlin to escape the restraints on artistic freedom in China.

Police detained Ai on Sunday morning, and his assistants and attorneys said they were concerned that they have not had any communication with him since. After his arrest, police blocked off the streets to his studio and raided it, carting away laptops and the hard drive from the main computer, Ai’s workers said.

They said eight staff members and Ai’s wife, Lu Qing, were taken to the local police station for questioning. Even as night fell, Lu and two staffers were still being held, they said.

Liu Xiaoyuan, a lawyer, said he hoped Ai’s international fame would provide him some protection while in police custody.

Liu also said the arrest appears to be “related to the intense international situation, such as what happened in Egypt, Libya and other Middle Eastern countries.” But he said it was too early to say whether Ai’s Twitter posts and interview statements about jasmine rallies in China played a part.

On Feb. 24, amid an online campaign for Middle East-style jasmine rallies in major Chinese cities, Ai posted on his Twitter account: “I didn’t care about jasmine at first, but people who are scared by jasmine sent out information about how harmful jasmine is often, which makes me realize that jasmine is what scares them the most. What a jasmine!”

Twitter is blocked in China, except for those with a virtual-private-network line or an Internet connection from outside the country. Ai has 72,000 followers.

Researcher Zhang Jie contributed to this report