AKIPRESS.COM - A plane carrying the chief executive of the world's biggest oil exporter was prevented from landing in the Chinese capital of Beijing on Tuesday because of thick smog blanketing large swathes of northern China, Reuters reported.

Amin Nasser, CEO of the Saudi Arabian oil producer Aramco, was due to attend an event on Saudi culture at Beijing's National Museum. But company officials said his plane was diverted after a fourth day of heavy smog led to the cancellation of more than 300 flights.

China declared a "war on pollution" in 2014 amid concern its heavy industrial past was tarnishing its global reputation and holding back its future development. But it has struggled to reverse the damage done by decades of breakneck economic growth, much of it based on the coal-burning power sector.

Despite months of efforts to hone its rapid response systems, air quality deteriorated in parts of the region on Tuesday, with the environment ministry warning that firms were flouting emergency restrictions.

Some power plants and chemical producers had not scaled back operations in line with regulations, according to China Environmental News, the official publication of the Ministry of Environmental Protection.

The paper said as many as 24 cities had issued pollution "red alerts" by Tuesday, but despite the implementation of emergency measures, smog concentrations had increased in some places.

They included several major cities in the industrial province of Hebei, which surrounds Beijing. Red alerts are issued when an air quality index (AQI) is forecast to exceed 200 for more than four days in succession, 300 for more than two days or 500 for at least 24 hours.

In Handan, a major steel producer, the 24-hour average AQI at one monitoring station reached a record 780, according to environmental group Greenpeace.

"The scale of the red alert measures show that the Chinese government is taking air pollution seriously," said Greenpeace climate and energy campaigner Dong Liansai.

"However, the ongoing 'airpocalypse' is further evidence that China must implement far stricter limitations on coal consumption and accelerate the restructuring of the economy away from the heavily polluting sectors," Dong said.