The meteorological administration said a sandstorm that swept down from the Gobi desert Friday would continue to shroud parts of northern China stretching from the far-western region of Xinjiang to Beijing.

"We advise friends in these areas to reduce their outdoor activities as much as possible," the administration said on its website.

"When you go out, please wear items to protect against the sand such as cotton cloths, masks and glasses to avoid the sand harming your eyes and respiratory system."

Sandstorms are an annual occurrence in arid northern China in the spring, when temperatures start to rise, stirring up clouds of dust that can travel across China to South Korea and Japan, and even as far as the United States.

Scientists blame a combination of deforestation, prolonged drought and resulting increase in desertification in northern China.

The sandstorm's impact stretched all the way to Hong Kong in southern China, where the government said it contributed to record air pollution on Monday.

On Saturday, South Korea warned residents of the capital Seoul as well as central and western regions to stay indoors due to the storm, Yonhap news agency reported.

In Beijing on the same day, authorities issued a rare level-five pollution warning, signalling hazardous conditions.

The respiratory department at Chaoyang Hospital, one of the city's biggest, said it had seen more than 180 people come with health problems -- 20 percent more than on a usual day, state media reported.

The capital was still cloaked in a mustard-yellow haze on Monday and residents complained of coughing and noses clogged with grit, though the administration said the sandstorm was weakening.

The storm comes as a severe drought grips the country's southwest, leaving an estimated 20 million people short of drinking water.

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