China retaliated in a widening trade war with the US, with a market regulator opening a probe into alleged antitrust violations by Google, the same day tariffs on mainland imports went into effect, South China Morning Post reported.

The State Administration for Market Regulation (SAMR) stated in a one-line entry on its website an investigation was prompted by suspicion of the search giant violating China’s anti-monopoly law, the newspaper wrote.

The US government, under new President Donald Trump, unveiled 10 per cent tariffs on Chinese products over the weekend. China has announced duties on coal, crude oil, LNG, agricultural equipment and some automobiles from the US, effective 10 February.

Google stopped offering its search in China in 2010.

In mid-December, days following the US widening export controls to limit Chinese companies’ access to advanced chips, the SAMR opened a probe into Nvidia for allegedly violating anti-monopoly laws, escalating rising trade tension between the two nations.