The US Senate passed a resolution calling on China to release jailed Tibetan monk Tensin Deleg Rinpoche and other political prisoners.
"Their only crime was peacefully serving the community of Tibet," said Senator Sam Brownback, the sponsor of the measure.
"It is time for the government of China to stop holding innocent religious figures in captivity merely for peacefully protesting China's occupation of Tibet," said Brownback, who is chairman of the Senate's East Asia Subcommittee.
Tensin Deleg, 52, was arrested in April 2002, for an April 2002 bomb attack in Sichuan's capital Chengdu, in which one person was killed and another injured.
In a closed door trial, he and another monk, Lobsang Dhondup, were also found guilty of further explosions in the Ganzi region of west Sichuan.
Both men denied the charges, and the case prompted an international outcry.
Lobsang Dhondup, 28, was executed in January 2003.
Tensin Deleg, 52, who was sentenced to death in December 2002, was given a two-year suspended sentence, which is normally reduced to life imprisonment.
Officials in Beijing, which has ruled Tibet for half a century, have refused to say whether Tensin Deleg's life would be spared, however, calling him a "terrorist."
The human rights group the International Campaign for Tibet estimates that there are 150 political prisoners in Tibet, about three-fourths of whom are monks and nuns. Many are subjected to physical and mental torture, isolation, and death, the group said.