BEIJING - Sixty-five officials have been punished for failing to meet air pollution control requirements in Northeast China's Heilongjiang province, according to the Ministry of Ecology and Environment.

They are accused of failing to implement the work arrangement by central authorities to guarantee air quality during the autumn-winter period last year, the ministry said in an online statement Tuesday.

Heavy air pollution was experienced last October in the cities of Harbin, Jiamusi, Hegang and Shuangyashan, the top environment watchdog said.

Investigation by the ministry's predecessor, the environmental protection ministry, found that provincial and local authorities did not effectively rein in extensive straw burning, which sent air pollution "off the charts."

Farmers often burn straw after the autumn harvest and plough the ashes into the soil to fertilize the land, but the practice is blamed for being a major cause of smog.

Those held responsible, including eight department-level officials, received disciplinary punishment, according to the ministry.

Tackling pollution is one of the "three tough battles" that China aims to win in the next three years, alongside reducing financial risk and eliminating poverty.