The probes into alleged disruptions to the global supply chain and trade of "green products" were "in response to the two US Section 301 investigations against China", a commerce ministry spokesperson said in a statement.

The United States launched trade investigations this month into dozens of countries, including China, centred on overproduction and importing goods made with forced labour.

The efforts came weeks after the US Supreme Court struck down President Donald Trump's global tariffs, saying he had exceeded his authority in tapping emergency economic powers to impose them on virtually all countries.

China had called those "Section 301" investigations -- which target foreign trade -- "political manipulation".

Beijing's commerce ministry said on Friday it would "take corresponding measures in accordance with the investigation situation (and) firmly safeguard its own legitimate rights and interests".

Both investigations would "conclude within six months" but may be extended up to three months, it added.

The White House has said Trump will visit Beijing from May 14-15, with the timing postponed by several weeks as a result of the war in the Middle East.