China launched the world's first quantum satellite, which will help it establish "hack-proof" communications between space and the ground, state media said, the latest advance in an ambitious space program.

The program is a priority as President Xi Jinping has urged China to establish itself as a space power, and apart from its civilian ambitions, it has tested anti-satellite missiles.

The Quantum Experiments at Space Scale, or QUESS, satellite, was launched from the Jiuquan Satellite Launch Centre in the remote northwestern province of Gansu in the early hours of Tuesday, the official Xinhua news agency said.

"In its two-year mission, QUESS is designed to establish 'hack-proof' quantum communications by transmitting uncrackable keys from space to the ground," it said.

"Quantum communication boasts ultra-high security as a quantum photon can neither be separated nor duplicated," it added. "It is hence impossible to wiretap, intercept or crack the information transmitted through it."

The satellite will enable secure communications between Beijing and Urumqi, Xinhua said, referring to the capital of China's violence-prone far western region of Xinjiang, where the government says it is battling an Islamist insurgency.

"The newly-launched satellite marks a transition in China's role - from a follower in classic information technology development to one of the leaders guiding future achievements," Pan Jianwei, the project's chief scientist, told the agency.

Quantum communications holds "enormous prospects" in the field of defense, it added.

China insists its space program is for peaceful purposes, but the U.S. Defense Department has highlighted its increasing space capabilities, saying it was pursuing activities aimed to prevent adversaries from using space-based assets in a crisis.