Most major Chinese cities continue to suffer heavy air pollution, but cleanup efforts are showing signs of progress, the country's environmental watchdog said on Wednesday.

Only three out of 74 cities that adopted revised air quality standards made the mark last year, Li Ganjie, vice-minister of environmental protection, said during the release of the 2013 Report on the State of the Environment in China.

Haikou in Hainan province, Zhoushan in Zhejiang province and Lhasa in the Tibet autonomous region reached the new air quality standards, according to the report.