According to sources with the State Administration of Work Safety, a homemade Yun-5 jet crashed on Tuesday in East China's Shandong Province when spraying chemicals against the locusts there.

The two pilots died.

The ministry said it is continuing to move urgently to fight the locusts which have become "disastrous" in 14 northern provinces and municipalities.

In some spots, the density of the insects has reached 4,000 to 5,000 per square meter, according to a report from Xinhua News Agency.

Vice-Minister Liu Jian, who leads the ministry's locust-plague control headquarters, said the northern parts of the country, due to years of drought and a deteriorated environment, are suffering a rampant locust invasion. The insects cover 2.7 million hectares of cropland, an increase of 10 percent over the same period last year.

Suburbs of Beijing, such as Miyun County and Huairou District, have seen locusts but little cropland was invaded, according to China News Service.

The report quoted the experts' view that the capital is not threatened thanks to the "isolation belt" around the city.

The central government has allocated a special fund of 500 million yuan (US$60 million) to help the local authorities cope with the disaster, according to the ministry.

Liu required local governments to take immediate action against the locusts, saying it is better to kill the pests before they start to fly.

The ministry also stressed the safety of the fight against the locusts, highlighting the secure use of jets and chemicals.

Li urged the further exploration of biological means of eradication, such as breeding ducks to eat locusts, instead of spraying insecticide.