BEIJING The wife of imprisoned Nobel Peace Prize winner Liu Xiaobo said Tuesday that the Chinese police guarding her home had confined her without any legal explanation, and she had no idea when she’d be freed.

As Liu Xia spoke, the U.S. Embassy in Beijing called for her release, but the Chinese government refused to discuss her detention.

Most Chinese still have no idea that the Peace Prize was awarded to her husband, a Chinese citizen.

Speaking on a cell phone brought by a family member, Liu Xia told McClatchy Newspapers that although she hasn’t been arrested, police ordered her not to meet with friends or speak with the news media. She said that to visit family or buy groceries, she must travel by police car under close supervision.

“I don’t know when they will let me go,” said Liu Xia, who’s been under guard since Friday’s award announcement. “The police don’t know, either; they’re just waiting for their orders.”

Mo Shaoping, whose law firm represents Liu Xiaobo, said that Chinese law didn’t support Liu Xia’s de facto house arrest.

“In China, it’s something used to confine citizens’ freedom,” Mo said. “There’s no legal term for this.”

The situation – Liu Xia’s detention and her husband sitting in prison – highlights the contrast between senior Chinese leaders’ comments about the government’s desire to proceed with civil reform and the often harsh reality for dissidents who call for such change.

In an interview with CNN that aired earlier this month, Chinese Premier Wen Jiabao said, “The people’s wishes for and needs for democracy and freedom are irresistible.” He stressed the need for all in China, including the government, to follow the law.

The United States urged China to restore Liu Xia’s freedom of movement. “We remain concerned by multiple reports that Liu Xia is being confined to her home in Beijing,” a spokesman for the U.S. Embassy in Beijing, Richard Buangan, said in an e-mail message to McClatchy. “Her rights should be respected, and she should be allowed to move freely without harassment.”

China’s government slammed the prize as an insult to Chinese justice.

“This is not only disrespect for China’s judicial system, but it also puts a big question mark on their true intentions,” Foreign Ministry spokesman Ma Zhaoxu said Tuesday.

To punctuate their displeasure, Chinese officials the day before had canceled talks with the Norwegian fisheries minister on short notice.

The Nobel Peace Prize committee in Oslo said that its choice of Liu Xiaobo for the award was meant to highlight the lack of human rights in China. Liu is serving an 11-year sentence for his role in drafting a political manifesto that calls for greater political and human rights protections in China.

So far, China’s response has been to keep Liu in prison, hold his wife under police guard, threaten many other dissidents to keep their mouths shut and suppress unauthorized domestic reporting about the prize.

China initially blocked all reports of Liu Xiaobo’s prize, then over the weekend domestic publications carried a Foreign Ministry statement that Liu is a criminal.

The information vacuum seems to have worked. During interviews in central Beijing this week, few people had heard of Liu or the award.

“Liu Xiaobo? I don’t know who that is,” said Li Tangsheng, 61, who was selling newspapers at a stand.