Yellow gale continued to sweep regions in Northwest China on Sunday, after severe sandstorms hit Gansu province and killed three people in the Xinjiang Uygur Autonomous Region over the weekend.

Southern Xinjiang, western Gansu, western Inner Mongolia and some parts of Ningxia will still be covered in dust on Monday, but sandstorms will gradually weaken and end on Tuesday, national meteorologists said.

In Xinjiang, the gale caused a big fire and damaged 14,000 vegetable greenhouses, causing economic loss of 550 million yuan (US$80 million), local authorities said on Sunday. Apart from the three deaths in the region, one person was also left missing from the sandstorm, authorities said.

With the wind speed reaching at least 36 meters a second, the gale seriously damaged crops and vineries, which are major sources of income for Xinjiang residents.

A sandstorm also hampered rescue and relief work in quake-hit Yushu county of Qinghai province on Sunday.

Hundreds of rescuers headed for Yushu were stranded at Qinghai's Xining airport following sandstorms and heavy snow in Yushu, the Xinhua News Agency reported.

The air route from Xining Caojiabao Airport to Yushu has been dubbed a "lifeline of the air" because it serves as a major link for getting immediate relief and rescuers to Yushu, which was hit by a 7.1-magnitude earthquake on April 14.

A sandstorm shrouded the airport and filled its interior with sand and grit. All six daily flights from provincial capital Xining to Yushu were delayed, said a spokesperson for the Caojiabao Airport.

In Gansu, the sandstorm leveled 547 houses and damaged 812 others.

At 7:10 pm on Saturday, people in Minqin county could barely see anything in the strong wind, a situation local meteorologists called the "black wind."

"A strong wind with heavy sand hit me like a wall and the sky suddenly became dark," a Minqin resident said.

Strong sandstorms hit most of Inner Mongolia on Saturday afternoon, with wind speeds of up to 22 meters a second, said Sun Yuegang, a forecaster with the local meteorological bureau of Alashan League. Visibility was only 50 meters at the peak of the sandstorms.

Latest satellite maps show that the strong sandstorms over the weekend affected 6.7 million people and 135 million hectares of land in Xinjiang, Qinghai, Gansu and Inner Mongolia, China National Radio reported on Sunday.

A cold front from Xinjiang to Gansu and high temperatures in desert areas caused the sandstorms, experts said.

"Every year from March to May, the frequent cold air and high temperatures in deserts are likely to form sandstorms," said Qiao Lin, chief forecaster with the China Meteorological Administration.