China's treatment of Uighurs living in its western region of Xinjiang risks turning the area into a "time bomb", an exiled Uighur group has said.
Some Uighurs resent an influx of Chinese settlers to the region
The World Uighur Congress (WUC) issued the warning as China prepared to celebrate 50 years of rule in Xinjiang.
A separate video, allegedly made by the East Turkestan Liberation Organisation, said it would use all means possible to launch an armed struggle against China.
China brands such groups terrorists and has vowed to crack down on separatists.
Concern over the situation in Xinjiang prompted the US to issue a statement on Friday warning American travellers in the region to be vigilant against an attack there, saying: "terrorists do not distinguish between official and civilian targets".
Xinjiang is home to a large population of Muslim Uighurs, many of whom continue to want an independent homeland, and resent the recent and large-scale influx into the region of Han Chinese settlers.
Ethnically Turkic Muslims, mainly in Xinjiang
Made bid for independent state in 1940s
Sporadic violence in Xinjiang since 1991
Uighurs worried about Chinese immigration and erosion of traditional culture
China says it has at least partly controlled Xinjiang for thousands of years, but Beijing's control on the region increased markedly after the establishment of the People's Republic in 1949, when troops occupied the area.
An autonomous local government was set up on 1 October 1955, and has ruled - under control from Beijing - since that time.
The central government insists it has raised living standards in Xinjiang over that time.
"Only under the leadership of the Communist Party of China... can Xinjiang have a better future," the state-controlled People's Daily reported on Friday.
But Uighur activists disagree. The German-based World Uighur Congress said 1 October should instead be a day of mourning.
"The policies of political oppression, cultural assimilation, economic exploitation, ecological destruction, racial discrimination have gradually turned East Turkestan into a time bomb," it said in a statement.
On Thursday, China's top security official Luo Gan warned of a new crackdown on "separatism" in the region, telling officials to "be prepared for danger".
Rebiya Kadeer denies trying to sabotage the anniversary
According to the China Daily, Mr Luo also added, however, that the general situation in Xinjiang was very good.
The authorities last month accused a prominent Uighur businesswoman-turned-activist, Rebiya Kadeer, who was recently freed from jail under intense international pressure, of planning to sabotage the forthcoming ceremonies.
But Ms Kadeer, who is now in exile in the United States, refuted that suggestion, telling the BBC: "I am involved in peaceful struggle for the people of the Uighur nation."