A month after the conviction of Australian citizen Stern Hu for taking kickbacks and stealing trade secrets, China has issued definitions of what constitutes commercial secrets.

The definitions, drawn up for China's hundreds of state-owned firms, are in line with a draft law that requires telecommunications and internet operators to give authorities access to information sent through their networks.

The draft is part of an effort to codify what is a secret in China after the trial of four Rio Tinto employees drew international attention to the country's vague secrets laws.

Those laws have long concerned human rights advocates.

Regulations on commercial secrets issued by the State-Owned Assets Supervision and Administration Commission (SASAC) were dated March 25, the day after the trial of Rio Tinto's Shanghai-based iron ore managers.

They were published late on Monday.

China's lack of clarification of state or commercial secrets, highlighted by the Rio employees' trials, has alarmed both Chinese and foreign investors.

The issue is of particular concern to businesses because state-owned enterprises, which dominate many industrial sectors, are both competitive-listed entities and an integral part of the state-directed economic model China imported from the Soviet Union.

Negotiations with those firms, therefore, can easily touch on matters the Chinese state deems of national interest.

Commercial secrets for state-owned firms, according to a notice posted on SASAC's website, include information relating to strategic plans, management, mergers, equity trades and stock market listings.

It also includes information related to reserves, production, procurement and sales strategies, financing, negotiations, joint-venture investments and technology transfers.

The regulations prevent information from being secret forever by requiring the company to define the period for which information is classified as either a "core commercial secret" or a "standard commercial secret".

The regulatory publications comes after China's third legislatory amendment to the law on guarding state secrets was updated to include communications through modern networks.

But legal and rights advocates contend the ruling Communist Party uses secrets laws to prosecute critics and people who reveal information embarrassing to the party or powerful individuals.

- Reuters