Seoul: Yellow sand mixed with toxic dust from China spread across South Korea on Monday, causing the closure of schools, while some factories stepped up safety precautions.

The annual "yellow dust" spring storms, which originate in China's Gobi Desert before sweeping south to envelop the Korean peninsula and parts of Japan, are blamed for scores of deaths and billions of dollars in damage every year in South Korea.

The country issued a yellow dust warning at the weekend. On Monday, school districts in southeastern regions urged parents to keep kindergarten and elementary school children at home.

An official with the Meteorological Administration said the first major storm of the season, which has also hit parts of Japan, was dispersing, but some reports said forecasts from China said cold air and little rainfall would lead to more storms from Wednesday through to March 11.

The sand storms have been increasing in frequency and toxicity over the years because of China's rapid economic growth and have added to increased tensions with neighbours South Korea and Japan over recent years.