The proportion of listed companies that disclosed environmental information fell slightly last year, a report has found.

The report, jointly published by Beijing University of Chemical Technology and the China Forum of Environmental Journalists, said only 1,006 — or 25.5 percent — of the 3,939 companies listed in Shanghai and Shenzhen disclosed their environmental report, or their corporate social responsibility report or corporate sustainability report, which can also include environmental information.

The ratio stood at just over 26 percent in 2018.

It also said that 139 of the companies that didn't disclose environmental information last year don't even have official websites.

A guideline published by the People's Bank of China, the country's central bank, in July 2017 said disclosure of environmental information — including things like pollutant emissions, green financing and environmental protection activities — will be mandatory for listed companies from the start of next month.