Liu Xia, 57, has been under de facto house arrest -- despite facing no charges -- ever since her husband was awarded the Nobel Peace Prize in 2010, a recognition that deeply angered the communist regime.
The group of 82 released videos on Wednesday of themselves reading excerpts of Liu Xia's poetry as part of a campaign for her freedom.
They included Nobel literature prize laureate JM Coetzee, Pulitzer prize-winning novelist Chabon, American novelist Auster and Chinese-born writers Hu Ping and Ma Jian.
Hosseini, author of "The Kite Runner", said in a statement: "As artists who are free to speak (we) must do so on behalf of other artists whose voices are being stifled."
Liu Xia faces daily restrictions on movement and surveillance, although Chinese authorities maintain she is free.
Her friends told AFP she is taking medication for depression and has suffered heart problems and fainting.
Liu Xiaobo, a veteran of the 1989 Tiananmen Square protests, died last year while serving an 11-year jail sentence for "subversion", making him the first Nobel laureate to die in custody since the era of Nazi Germany.
The campaign for the widow's release came two weeks after reports emerged that Liu had told a friend she was ready to "die at home" in protest at her continuing detention.
Suzanne Nossel, PEN America executive director, said: "Liu Xia's cry for freedom resonates around the world and rebukes the Chinese government's hollow claim that she is free."
The video campaign was jointly organised by PEN America and Amnesty International.
Diplomats from the French, German, Canadian, British and European Union embassies tried to visit her at her Beijing apartment last Friday amid growing concerns about her psychological health.
But security guards prevented them from seeing her and China's foreign ministry later warned foreigners not to interfere.
"Liu Xia is a Chinese citizen. The relevant departments of the Chinese government of course protect her rights according to Chinese law," foreign ministry spokesman Lu Kang said Monday.
The German embassy offered in April to help her travel to Germany but the move did not take place, according to Chinese writer Liao Yiwu, who is close to Liu Xia.
AFP reporters have tried to visit Liu's home multiple times in recent years but were blocked each time by plainclothes men.
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