New swarms of locusts in southern Ethiopia and northern Kenya are spreading further in the eastern Africa region, the UN’s Food and Agriculture Organization (FAO) has warned.

In its latest update posted on Monday, FAO said the immature swarms have been migrating from the previous locust breeding grounds in eastern Ethiopia and central Somalia and spreading into Ethiopia’s SNNP region and into Kenya’s northern and coastal counties.

“So far, swarms are present in four (Kenyan) counties (Wajir, Garissa, Marsabit and, most recently, Isiolo). Breeding continues, and hopper bands are present in the southeast near Taita Taveta and along the coast,” FAO says

A few swarms could spread further in Kenya and reach Tanzania, South Sudan and Uganda this month, the FAO warns.

Locust invasion poses a big threat to food security in the region. Last year, the region saw billions of the insects destroying crops across the region.

The UN agency has urged countries affected to take the necessary efforts to survey, control reduce migration and breeding of the insects.

The FAO says is a moderate risk the swarms "could reach central Kenya and perhaps the southwest as well as northeast Tanzania, eastern Uganda, and southeast South Sudan during January".

Already, the agency says, there are reports of some immature swarms reaching Mwanga district in northeast Tanzania on 8 January.

"Once swarms arrive in favourable areas, they will mature and lay eggs that will hatch and cause hopper bands to form during February and March," FAO says.