CHINA has installed anti-ship cruise missiles and surface-to-air missile systems on three of its outposts in the South China Sea, US news network CNBC reports, citing sources with direct knowledge of US intelligence reports.

The move, if confirmed, would mark the first Chinese missile deployments in the Spratly Islands, where several Asian countries including Vietnam and Taiwan have rival claims.

Foreign Affairs Minister Julie Bishop said the Australian Government would be “concerned” if the reports were accurate.

The Minister refused to comfirm or deny any Australian intelligence about the missiles.

But she said: “If the media reports are accurate, then the Australian Government would be concerned because this would be contrary to China’s stated aspiration that it would not militarise these features.”

“China of course has a unique responsibility as a permanent member of the [UN] Security Council to uphold peace and security around the world and any action to militarise unilaterily features in the South China Sea would go against that responsibility in that role.”

Chinese officials did not immediately respond to requests for comment.

CNBC quoted unnamed sources as saying that according to US intelligence assessments, the missiles were moved to Fiery Cross Reef, Subi Reef and Mischief Reef within the past 30 days.

According to an expert, the move suggests China will probably send warplanes to the region soon as well.

Gregory Poling, Center for Strategic and International Studies fellow and director of the Asia Maritime Transparency Initiative told CNBC, “This should be seen as China crossing an important threshold. Missile platforms present a clear offensive threat.

He said it also furthers China’s goal of “establishing complete control over the water and airspace of the South China Sea”.

The US Defence Department, which opposes China’s installation of military facilities on outposts it has built up in the South China Sea, declined comment. “We don’t comment on matters of intelligence,” a spokesman said.

China has made no mention of any missile deployments but says its military facilities in the Spratlys are purely defensive.

Poling said such deployments were expected as China built missile shelters on the reefs last year and already deployed such missile systems on Woody Island further to the north.

“Before this, if you were one of the other claimants ... you knew that China was monitoring your every move. Now you will know that you’re operating inside Chinese missile range. That’s a pretty strong, if implicit, threat.”

CNBC said the YJ-12B anti-ship cruise missiles allowed China to strike vessels within 295 nautical miles. It said the HQ-9B long-range surface-to-air missiles could target aircraft, drones and cruise missiles within 160 nautical miles.

Last month, US Admiral Philip Davidson, nominated to head US Pacific Command, said China was now capable of controlling the South China Sea “in all scenarios short of war with the United States,” he said.