BEIJING, Aug. 1 (Xinhua) -- Leading government officials of five localities in north China were called in Wednesday by the environment watchdog for talks over failing to meet air improvement targets.

The Ministry of Ecology and Environment (MEE) found 5,204 air quality problems after conducting two rounds of inspections in the Beijing-Tianjin-Hebei region and adjacent areas from June 11 to July 8, said Liu Changgen, deputy director of the national environmental inspection office.

Major problems were found in Quyang county, Hebei province, Tongzhou District in Beijing, Zhaoxian county in Hebei, Jincheng, a city in eastern Shanxi, and Huixian County in Henan province.

The environmental inspectors found the air pollution was caused by illegal use of outdated boilers, dust pollution, and the use of vehicles that failed to meet sanitation standards, according to Xia Zuyi, deputy head of the environment supervision department of the MEE.

More inspections would be carried out this fall and the coming winter, said Liu, who warned that those in violation of the rules will be held accountable.