China's anti-monopoly regulator has said it had launched an investigation into Alphabet's Google, minutes after an additional 10 percent tariff on Chinese goods imposed by US President Donald Trump came into effect.

The investigation by China's State Administration of Market Regulation was announced as Beijing also slapped tariffs on some US products such as coal and oil in a rapid response to the new US duties on Chinese goods.

The Chinese regulator said Google was suspected of violating the country's anti-monopoly law, and it had initiated an investigation into the company in accordance with the law.

It did not offer any further details on the investigation or on what it alleged Google had done to breach the law.

Google products such as its search engine are blocked in China, but it works with local partners such as advertisers in the country.

Google did not respond immediately to a request for comment.

'Unreliable entities'

Google in 2011 abandoned its Chinese-language search engine in the mainland and transferred it to Hong Kong.

By 2014, China blocked the last remaining way to access Google's email service Gmail.

Beijing also said it would add US fashion group PVH Corporation which owns Tommy Hilfiger and Calvin Klein and biotech giant Illumina to a list of "unreliable entities".

The move would "safeguard national sovereignty, security and development interests, in accordance with relevant laws", China's commerce ministry said in a statement.

"The above two entities violate normal market transaction principles, interrupt normal transactions with Chinese enterprises, and take discriminatory measures against Chinese enterprises," it added.

China in September said it was investigating PVH for an "unreasonable" boycott of cotton from its Xinjiang region.