The wreckage of US and Russian satellites that collided over Siberia poses a threat to China's satellites in orbit, but the country's space plan will proceed as scheduled.

A privately owned US communications spacecraft collided with a defunct Russian military satellite about 800 km above northern Siberia at 4:55 pm GMT on Tuesday, according to the US Strategic Command, which made it public on Wednesday.

The 560-kg US satellite, of Iridium Holdings LLC, was launched in 1997 and the Russian Cosmos-2251, weighing almost a ton, was sent in space in 1993.