Companies were urged to release more information on pollutant discharge than the legal minimum required, to meet growing public demand for transparency.

The call, by an environment official, was made as Tianjin launched a pilot project that encourages industrial companies to voluntarily release environmental data and map out the transfer of pollutants for the public to track.

Bie Tao, deputy director of the policy and regulation department under the Ministry of Environment Protection, welcomed the initiative in Tianjin and said it carried greater significance than before.

The economy still relies heavily on high-energy consumption and high-emission industries, and consequently faces growing environmental challenges during rapid industrialization, he said.

A long-awaited law aimed at tackling air pollution has been submitted to the State Council and is awaiting approval.

Bie said that means lawmakers are one step closer to imposing stricter requirements to ensure air quality.

Some companies are concerned that disclosing information on pollutants will harm their public image, he said, but recent cases have shown their image will suffer greater damage if they conceal such information from the public.

Managers of a chemical plant in Changzhi, Shanxi province, who were responsible for a toxic leak on Dec 31, have been suspended for a delay in reporting the accident.

Individuals and social organizations in nearby Handan, where water supplies were affected, are filing lawsuits against the plant.

"The case in Shanxi shows an environmental scandal can develop into a crisis of public trust for both a government and a company," Bie said.

China's regulation on the release of environmental information, which was introduced on a trial basis in 2008, requires companies to disclose environmental information. Companies that disclose such information will receive financial rewards from authorities.

Heavy polluting enterprises, with emissions above national or regional discharge standards, must disclose information on major pollutant emissions, the construction of environmental protection facilities, renovation and emergency plans.

Song Yuyan, director of the program in Tianjin, said there are 31 companies in the municipality's Binhai New Area that have disclosed environmental information in 2012, almost double the number of companies that did so in 2009.

But Song admitted the environmental reports released by these companies sometimes lack accuracy.

"The pilot program is to encourage more companies to take action and set up a widely recognized measure of disclosure for companies to follow, so that the data they release can be used as reference," she said.

It will be a gradual process, she added, and authorities will offer training and assistance.

Feng Yongfeng, founder of Green Beagle, an environmental protection NGO in Beijing, said companies are afraid to release environmental information, especially those listed on stock exchanges.

He suggested inviting a third-party assessment system for the Binhai program.

Contact the writers at [email protected] and [email protected]

Wang Yuke in Tianjin contributed to this story.