Chinese rocket to tumble back to Earth in uncontrolled re-entry.

Beijing -- A large segment of a Chinese rocket is expected to make an uncontrolled re-entry into the Earth's atmosphere over the weekend, but Beijing has downplayed fears of damage on the ground and said the risk is very low.

A Long March-5B rocket launched the first module of China's new space station into Earth's orbit on April 29.

Its 18-tonne main segment is now in freefall and experts have said it is difficult to say precisely where and when it will re-enter the atmosphere.

Russian space agency Roscosmos predicted the rocket will re-enter after 2330 GMT Saturday south of Indonesia over the Timor Sea.

The Pentagon gave a time of around 2300 GMT Saturday with a window of nine hours either side.

Chinese authorities have said most of the rocket components will likely be destroyed as it descends.

"The probability of causing harm... on the ground is extremely low," Chinese foreign ministry spokesman Wang Wenbin told reporters on Friday.

Although there has been fevered speculation over exactly where the rocket -- or parts of it -- will land, there is a good chance any...