The Foreign Ministry said China would take whatever measures are necessary to protect the legitimate rights and interests of the country's companies.

"The United States should abide by the market regulation of fair competition and stop politicising economic and trade issues," ministry spokesman Lin Jian said.

The ministry was responding to Wall Street's top regulator taking a step towards toughening rules for foreign companies listed on American stock markets.

The US Securities and Exchange Commission said many Chinese firms in particular benefited from having to make fewer regular disclosures to investors.

It voted unanimously to call for public comment on possible new regulations that would narrow the definition of those foreign companies, known as foreign private issuers, that are required to publish only annual reports and occasional updates.

US firms trading on the same stock exchanges fall under the full scope of American securities laws, including quarterly financial reporting, proxy solicitation rules and prompt disclosure of events such as mergers and the departures of board members.

Any new regulations for foreign companies could make it more costly and challenging for many to tap US equity markets. (Reuters)