Nairobi (CNN) The Horn of Africa has been hit by the worst invasion of desert locusts in 25 years, the UN's Food and Agriculture Organization (FAO) said Friday.

The invasion poses an unprecedented threat to food security in the entire sub region, where more than 19 million people in East Africa are already experiencing a high degree of food insecurity, the agency said.

In Kenya, it is the worst invasion in 70 years, and the government is spending $5 million to manage the swarms of locust and prevent spreading.

Invasions of desert locusts are irregular in the region, the last instance occurred in 2007 at a much smaller scale.

"This current invasion of desert locust is significantly larger in magnitude and scale than previously experienced in Kenya and across East Africa," said Dr. Stephen Njoka, the Director General of Desert Locust Control Organization.

Read More