A US-based Uighur association condemned the death sentences of four of their countrymen in connection with July's ethnic riots, in a statement released Wednesday in Washington, DPA reported.
The Uyghur American Association (UAA) said the convictions on Monday by a court in Urumqi, in the north-west of the country, were the result of "unfair trials, a politicized judicial process and a lack of judicial transparency."
Courts in the Chinese region of Xinjiang have condemned 26 people to death for participating in last year's ethnic clashes, according to the association.
Chinese state media said in November that the executions of eight Uighurs and one Han Chinese had already been carried out. Official statements this week indicated that Monday's sentences would be executed immediately.
Another defendant was sentenced to death Monday but was granted a two-year stay of execution, a sentence usually commuted to life in prison.
According to the UAA, the names of all five of the condemned indicate they are ethnic Uighurs.
"An unknown number of Uighurs were killed by security forces in July or have died in prison since that time," exiled Uighur community leader Rebiya Kadeer said. "The Chinese government must end this cycle of death and execution," she said.
Clashes between different ethnic groups and with the police rocked Urumqi, capital of China's Xinjiang Uighur Autonomous Region, left 197 people dead according to official figures.
The region is home to 8 million Uighurs and 7 million Han Chinese. Kazakhs and other ethnic groups make up a further million inhabitants.
After a brief period of independence as the Second East Turkestan Republic, the area has been incorporated into the People's Republic of China since 1949.