The Chinese authorities have declared more red alerts in at least 10 cities after hazardous smog blanketed the nation’s north-east.

The announcement which advises residents to stay indoor follows last week’s warning that a vast area of China will be severely hit by pollution.

Beijing saw its second red alert over the weekend. The latest wave of alerts includes the industrial port, Tianjin.

Red alerts trigger advisories for people to stay inside, schools to stop classes, and restrict vehicle use.

According to reports, the 10 cities hit with the red alerts in China include Tianjin, Puyang, Xinxiang, Dezhou, Handan, Xintai, Langfang, Hengshui, Xinji and Anyang.