Swarms of locusts have infested parts of northeastern Kenya's district of Mandera, ravaging pasture and crops in the arid area frequently hit by drought, officials said.

The locusts reportedly originated from neighbouring Somalia where authorities in the northeastern self-declared autonomous region of Puntland in September appealed for international aid following the loss of thousands of hectares of pasture and farmland to locust infestation.

Mandera District Commissioner Naftali Mung'athia said the pests had destroyed crops on smallholder farms along the River Dauwa that forms the border between Kenya and Ethiopia. He said a team of officials from the ministries of agriculture and livestock were carrying out an assessment of the infestation.

"Some damage has already been done, but we are confident the situation will be contained," said Mung'athia. The most affected areas were Kalalio and central divisions of Mandera District, he added.

Dahabo Daud, an official of Mandera Women for Peace, a community-based organisation, said that more than 200 families who depended on riverine cultivation of vegetables and some cereals had lost their crops to the locusts and were in need of assistance.

Mohamed Ibrahim, a livestock keeper in Mandera, a district inhabited mainly by ethnic Somali pastoralists, said he was worried that shortages of pasture as a result of the locust infestation would hit the area again.

Mandera was one of the areas in northern and northeastern Kenya ravaged by a devastating drought in 2006.

"We got enough rains a month ago and we were not worried about drought which killed many animals, but now things have changed," said Ibrahim.