BEIJING, Nov. 4 -- China's Ministry of Environmental Protection (MEP) on Tuesday summoned the mayor of Anyang City in central China's Henan Province to discuss the city's smog response measures, the latest in China's efforts to curb its smog problem before APEC meetings this week in Beijing.

Since June, the ministry has been monitoring the city, whose air quality ranked second-to-last among 18 Henan cities in 2013, according to a statement from the MEP. But without effective measures, some heavy polluters have refused to fix their practices.

At the discussion, the ministry urged Ma Linqing, the city's mayor, to submit an action plan within 15 days, take effective measures to reverse the pollution trend, and help ensure air quality for the APEC meeting.

Aside from a lack of supervision and punitive measures, the MEP said in the statement that a large number of cement factories, iron and steel mills and coking plants have contributed to heavy smog. Some factories have even secretly discharged pollutants at night.

MEP said the city also missed a good opportunity to remove heavy polluters during the summer.

Anyang is about 500 kilometers from Beijing. According to its official website, it had a population of over five million in 2010.

It is the second time the ministry has criticized the local government on smog response measures. In October, the ministry criticized eight cities in northern Hebei Province for inadequate emergency measures against air pollution.

Vice Premier Zhang Gaoli said last month that ensuring air quality for the APEC meeting is the "priority of priorities" for the current air pollution control work.