Odil Azizov, 25, died on May 4 in a prison hospital in the capital, Tashkent, where he had been moved from the Zhaslyk prison, his father said late last week.
Rights groups say Uzbekistan keeps most of its political prisoners at Zhaslyk, in a remote western desert.
Justice officials could not be reached for comment Thursday despite repeated attempts.
Azizov's father said his son's body was covered with signs of torture when it was handed over to him last Monday.
"I saw a large stain and bruises on the left side of his chest. ... His feet were swollen," Makhmud Azizov said by telephone from the eastern city of Kokand, where he lives.
"When he was dying I appealed to all government bodies for urgent surgical treatment, but nothing was done. ... [Prison officials] were just waiting for his death," he said, adding that his son had complained of mistreatment while serving his term.
Azizov was jailed in 2001 after a court charged him with crimes that included violation of the constitution, membership in an Islamic organization branded as terrorist by the Uzbek government and distribution of illegal religious books.
In a November 2007 report, the United Nations accused Uzbek police and prison staff of "routine use of torture" to extract confessions. The Uzbek government denies the accusations.
Surat Ikramov, a prominent Uzbek rights defender, said the situation in prisons was dire, with at least 20 inmates dying of various causes every month.
Uzbekistan's government is accused in the West of tolerating no dissent and allowing the use of torture in jails.
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