Beijing and neighboring Tianjin and Hebei province see more severe air pollution than the rest of the nation, the Ministry of Environmental Protection said in a report released on Tuesday.

Of the country's 20 most polluted cities, as many as 11 lie in the Beijing-Tianjin-Hebei city cluster, with seven of them among the 10 worst, according to 2013 air quality monitoring data provided by the environmental watchdog.

Many of the cities, including Xingtai, Shijiazhuang, Tangshan and Baoding, mostly in Hebei province, saw 40 percent of their days seriously polluted, it said.