US President Donald Trump has announced hefty tariffs on $US50 billion of Chinese import as Beijing responded in kind, escalating a trade dispute between the world's two largest economies.

Key points: Donald Trump vows further measures if Beijing strikes back

Donald Trump vows further measures if Beijing strikes back The tariffs would impact Chinese imports containing industrially significant technologies

The tariffs would impact Chinese imports containing industrially significant technologies China has threatened tariffs on US goods including soybeans, aircraft, and cars

Mr Trump, whose hard-line stance on trade has seen him wrangle with allies, said in a statement that a 25 per cent tariff would be imposed on a list of strategically important imports from China.

The US Trade Representative's (USTR) office said the tariffs would begin on July 6, and be implemented in two tranches.

About $US34 billion ($45 billion) worth of imports on a tranche of 818 product categories — excluding television sets and other consumer products — would the first to fall under the new rules.

A second tranche of tariffs on 284 product categories worth $US16 billion would go into effect at a later date after a public comment period.

Mr Trump also vowed further measures if Beijing struck back, but denied there was a trade war after announcing the tariffs.

"The United States will pursue additional tariffs if China engages in retaliatory measures, such as imposing new tariffs on United States goods, services, or agricultural products; raising non-tariff barriers or taking punitive actions against American exporters or American companies operating in China," Mr Trump said in a statement.

Hours after the announcement, China's official Xinhua news agency reported the country would impose an additional 25 per cent tariff on 659 US goods worth $US50 billion.

Tariffs on $US34 billion of US goods including agricultural products, automobiles and aquatic goods would take effect from July 6, Xinhua reported, citing the Tariff Commission of the State Council.

Tariffs on other US goods would be announced at a later date, according to Xinhua.

"The US decision has violated World Trade Organisation rules and is contrary to the consensus that China and the US reached in previous trade negotiations," Xinhua reported.

"It has also seriously damaged China's legitimate rights and interests and has harmed the interests of China and its people," according to the report.

Earlier, China's Commerce Ministry said the results from the negotiations previously reached by the US and China would be invalid.

Mr Trump has already said the United States would hit another $US100 billion of Chinese imports if Beijing retaliated.

Beijing and Washington have held three rounds of high-level talks since early May. ( AP: Andy Wong, Pool )

Beijing and Washington yet to reach a compromise

The tariffs would impact Chinese imports containing industrially significant technologies, including those related to China's "Made in China 2025" industrial policy.

"We must take strong defensive actions to protect America's leadership in technology and innovation against the unprecedented threat posed by China's theft of our intellectual property, the forced transfer of American technology, and its cyber attacks on our computer networks," Trade Representative Robert Lighthizer said in a statement.

"China's Government is aggressively working to undermine America's high-tech industries and our economic leadership through unfair trade practices and industrial policies like 'Made in China 2025'.

"Technology and innovation are America's greatest economic assets and President Trump rightfully recognises that if we want our country to have a prosperous future, we must take a stand now to uphold fair trade and protect American competitiveness."

China has also published its own list of threatened tariffs on $US50 billion in US goods, including soybeans, aircraft, and cars.

Beijing and Washington have held three rounds of high-level talks since early May that have yet to yield a compromise.

Mr Trump has been unmoved by a Chinese offer to buy an additional $US70 billion worth of US farm and energy products and other goods, according to people familiar with the matter.

The announcements came in the aftermath of Mr Trump's nuclear summit with North Korean leader Kim Jong-un and his push for China to maintain economic pressure on the North.

Mr Trump has already slapped tariffs on steel and aluminium imports from Canada, Mexico, Europe and Japan, drawing a rebuke from US allies.

ABC/wires