US President Donald Trump's national security adviser, John Bolton, says China's attempts to use think tanks and non-profit organisations to influence opinion in the US and Australia "is far greater in magnitude than any other foreign effort we have seen in history".
Mr Bolton also offered blunt assessments on China's island and military base building in the South China Sea and raised concerns "Manchurian" chips in Huawei technology could be activated for espionage.
Mr Bolton, in a US TV interview on Sunday, said China's efforts to influence opinion in America via Confucius Centres and other ways trumped Russia's election hacking.
"It really is far greater in magnitude than any other foreign effort we have seen in history to influence American opinion and it's not just confined to the United States," Mr Bolton told Fox News' Maria Bartiromo.
"They are doing it in Australia and other countries - close friends of ours.
"So this really goes to the core of how you maintain a free and open society in this country when other countries are trying to influence it the way that China has.
"It goes well beyond just election hacking although we certainly have been concerned about China doing that as well."
Mr Bolton, known for his hawkish views, became President Trump's national adviser after the departure of retired US Army general HR McMaster in April last year.
Mr Trump is expected to reveal his 2020 budget proposal to congress on Monday and Mr Bolton said handling the existential threat posed by China "has been a focus of much of the preparation of the budget requests".
He said China, through island building in the South China Sea, was in effect attempting to create a new Chinese province.
"It is taking over these rocks and shoals and islands and building military bases on them," Mr Bolton said.
"It is completely unacceptable.
"That is why we have continued to do freedom of navigation exercises and look at other ways to stop this effort in effect to create a new Chinese province."
Mr Bolton also backed concerns raised by the US, Australia and other countries about using Huawei technology for national security-related telecommunication systems.
"I think for very, very good reasons," he said.
"People sometimes call the concern the Manchurian chip problem - that if something gets into the telecommunications system that can be activated down the road.
"This is a very serious threat."
