BEIJING - China's environment authority on Tuesday exposed the grave pollution situation in Cangzhou, a north China city close to Beijing.

The Ministry of Environmental Protection (MEP) said Cangzhou, in Hebei province, was seriously polluted and the issue has become an obstacle to the integrated development of Beijing and neighboring Tianjin and Hebei.

According to the MEP, some Cangzhou factories dump their waste water without any treatment, often with excessive concentration of pollutants.

Over 30 small plants were found emitting "black smoke", and more than 500 casting workshops around Botou, a county-level locality in Cangzhou, were described as poor.

Moreover, PM 10 particle pollution and nitrogen dioxide in the city increased by 6.2 and 6.5 percent in 2014.

The water in the Bohai Sea adjacent to Cangzhou is polluted, with high readings of suspended solids, chemical oxygen demand (COD), and nitrates, the MEP said.

The MEP has discussed the pollution issue with Cangzhou City bosses and demanded a plan for radical improvements delivered to the MEP within 15 days.