Human rights groups are pressing China for the release of both Nobel Peace Prize Laureate Liu Xiaobo and his wife, who has been put under house arrest.
The Chinese authorities must immediately disclose the whereabouts of Liu Xia, Amnesty International said over the weekend.
The authorities have stepped up harassment of dissidents and human rights advocates since the award was announced in Norway.
Reports say there have been house arrests, the shutting down of telephones, and the breaking up of meetings.
Ms Liu was confined to her Beijing apartment without visitors or a telephone since being allowed to deliver news of the award to her husband, who is serving 11 years in a prison in northeast China.
She has been denied legal aid and forced to leave Beijing to visit her husband in Jinzhou in Liao Ning province, where he is imprisoned.
Catherine Baber, Amnesty International's Asia Pacific deputy director commented: “The Chinese authorities may want to play down the international focus Liu Xiaobo’s Nobel Peace Prize has placed on the thousands of prisoners of conscience held in China, but the harassment of Liu Xia is certainly not the way to achieve this."
She continued: “It is outrageous that Liu Xia be harassed just because her husband has received international recognition for his work for human rights. Her whereabouts must be disclosed immediately with confirmation that she remains a free citizen."
“The Chinese authorities would have far greater impact if they used this as an opportunity to release all those currently held in China for peacefully expressing their views and stopped harassing innocent citizens,” said the Amnesty spokesperson.
"Under no Chinese law can a family member of an imprisoned person be put under house arrest unless their is evidence that he or she has committed a crime," Ms Liu's lawyer, Ding Xikui, told reporters.
While she was still able to, Ms Liu used Twitter to tell people her husband was extremely moved when she told him about the Nobel award, and immediately dedicated it to all those who died in Tiananmen Square in 1989.
The Chinese authorities have blocked out reports of the prize in the media.