BEIJING (AP) – The wife of a Chinese dissident was detained at the airport by security agents Monday and barred from leaving the country to attend a human rights meeting in Switzerland, the activist said.

Hu Jia, who like most dissidents is under constant surveillance, has been largely confined to his home since last month after security agents stopped him and his wife from leaving China, saying they were a threat to national security.

Mr. Hu said his wife Zeng Jinyan, who is four months pregnant, was detained at the airport for two hours Monday.

“Plainclothes security officers came there and wouldn’t let her depart China because of the charges (that she is a security threat) and confiscated her travel documents,” he said in a telephone interview.

Ms. Zeng was released Monday afternoon but it wasn’t clear how long her passport would be held, said Hu, an AIDS activist.

China has been taking great pains to protect its image ahead of the 2008 Beijing Olympics, a source of great pride for the country. But in recent months, activist groups have used the games to bring attention to China’s handling of issues such as the Darfur crisis in Sudan and calls for Tibet independence.

“If in Europe we disclose proof of the Chinese government’s human rights violations, then it would be a heavy blow,” Hu said. “So I think this time, they’re strictly regulating not just me but my wife as well.”

Phones at the press office of the Ministry of Public Security rang unanswered Monday afternoon.