BEIJING (Reuters) - China said it was still facing “huge pressure” to meet politically crucial 2017 air quality targets, even as it spelled out more details on Friday of a six-month plan to cut smog this winter.

FILE PHOTO: Buildings are seen in heavy smog during a polluted day in Jinan, Shandong province, China, December 20, 2016. REUTERS/Stringer/File Photo

China has promised to close twice as many factories and enforce bigger emission cuts in coming months in a bid to avoid a repeat of the near-record levels of choking smog that enveloped key northern regions at the start of the year.

The Ministry of Environmental Protection (MEP), which last week published a 143-page plan on cutting emissions at 28 cities, said at a briefing that random spot checks will be used to ensure local governments and enterprises toe the line.

But in a summary of an internal meeting published on its website, it noted the difficulty of meeting targets set in 2013 aimed at assuaging public anger over damage to the environment after three decades of breakneck growth, with many areas still not up to scratch.

“The completion of the targets and tasks of the (2013) 10-point air quality action plan is still facing huge pressure,” the MEP said, citing environment minister Li Ganjie.

At the start of 2017, emissions of small hazardous particles known as PM2.5 hit near-record highs in Beijing and surrounding Hebei province, prompting the region to take emergency measures to thin traffic and curb industrial activity.

Liu Bingjiang, head of the MEP’s air quality department, said on Friday that China would take even sterner action this year ahead of the winter spike in coal usage.

“This is the first time we have made a detailed plan for autumn and winter and our targets are twice as high as last year,” he said, noting that as many as 44,000 coal-fired boilers will be shut down.

The government has expressed confidence that air quality would improve compared to last year, but emissions in the smog-prone Beijing-Tianjin-Hebei region have risen in the first seven months of 2017.

The MEP aims to reduce emissions of PM2.5 by at least 15 percent in the coming months, while the capital Beijing will be forced to reduce PM2.5 readings by more than 25 percent year on year over winter months to meet its targets.

Wary of the impact the crackdown will have on commodities markets, the ministry has warned local governments not to use a “one size fits all” approach to implementing environmental policies, but some prices have already surged.

Hebei is home to a quarter of national steel production, and its cities will be forced to cut output by as much as 50 percent over winter in a bid to reduce smog. Production of aluminum, glass and cement is also expected to take a big hit.