China will take counter-measures of the "same proportion" and scale if the United States imposes further tariffs on Chinese goods, China's ambassador to Washington has said, amid growing fears of an impending trade war.

Cui Tiankai made the comments ahead of what is expected to be the announcement this week of US tariffs on $50 billion to$60 billion in Chinese imports following an investigation under Section 301 of the 1974 US Trade Act.

"If they do, we will certainly take countermeasures of the same proportion, and the same scale, same intensity," Cui said in an interview posted on the website of China Global Television Network (CGTN) and broadcast on state television today.

The US tariffs are expected to target products benefiting from Beijing's "Made in China 2025" industrial development programme, although it may be more than two months before the import curbs take effect, US officials have said.

China on Sunday announced tariffs on $3 billion in imports of US food and other goods in response to US tariffs on imports of aluminium and steel, a skirmish that investors fear is a prelude to a broader trade war.

"China does not provoke a trade war, and doesn't want to fight a trade war, but we also aren't afraid of a trade war," Chinese Foreign Ministry spokesman Geng Shuang told a regular news briefing.

The Section 301 investigation initiated by US President Donald Trump is focused on accusations of theft of intellectual property and forced technology transfer by China, charges Beijing denies.

Cui said China has been bolstering its protection of intellectual property rights.

"China has been strengthening its efforts and strengthening our legal system on this particular issue, and we are making good progress," he said.