BEIJING (REUTERS) - A Chinese quantum satellite has dispatched transmissions over a distance of 1,200km, a dozen times further than the previous record, a breakthrough in a technology that could be used to deliver secure messages, state media said on Friday (June 16).

China launched the world's first quantum satellite last August, to help establish "hack proof" communications between space and the ground, state media said at the time.

The feat opens up "bright prospects" for quantum communications, said Pan Jianwei, the lead scientist of the Chinese team, Quantum Experiments at Space Scale (QUESS), according to the official Xinhua news agency.

The scientists exploited the phenomenon of quantum entanglement, in which a particle can affect a far-off twin instantly, somehow overcoming the long distance separating them, a situation termed "spooky action at a distance" by the Nobel-prize winning physicist Albert Einstein, Xinhua added.

The team had successfully distributed entangled photon pairs over 1,200km, it said, outstripping the distance of up to 100km at which entanglement had previously been achieved.

The technology so far is "the only way to establish secure keys between two distant locations on earth without relying on trustful relay," Pan told Xinhua, referring to encrypted messages.

The new development "illustrates the possibility of a future global quantum communication network" the journal Science, which published the results of the Chinese team, said on its website.

China still lags behind the United States and Russia in space technology, although President Xi Jinping has prioritized advancing its space program, citing national security and defence.

China insists its space programme is for peaceful purposes, but the US Defence Department has highlighted its increasing space capabilities, saying it was pursuing activities aimed at preventing adversaries from using space-based assets in a crisis.

China's launch of the first experimental quantum satellite was a "notable advance in cryptography research", the Pentagon said this month.