More than 40,000 people have fled recent clashes between two northern Kenyan tribes over access to water and pasture, the International Federation of Red Cross and Red Crescent Societies said Friday.

"Over 40,000 people have fled their homes in Moyale, northern Kenya," said Alexander Matheou, IFRC head for East Africa.

The UN had earlier said "tens of thousands" displaced by the fighting had fled into neighbouring Ethiopia, where the majority are living with host families.

Clashes between rival cattle herding pastoralists in the region are common, with herders often carrying guns to protect their animals, but the recent fighting has been unusually heavy.

The clashes pit two traditional rivals, the Borana and the Gabra, around the town of Moyale on the Ethiopian border.

"We have never seen before what we are seing this time, entire villages, entire schools destroyed, water points sabotaged," Matheou told AFP.

"Shops in Moyale are closed, houses, schools are empty, there is a very eerie sense like a ghost town," he added.

"Conflict between the Borana and Gabra clans in northern Kenya has displaced tens of thousands of people," the UN Office for the Coordination of Humanitarian Affairs said in a report Tuesday.

Food for 15,000 people has been sent to the area, along with plastic sheets and household items for some 3,000 people, it added.

Fighting over land grazing rights in the remote Moyale region killed at least 18 people last month after two days of intense violence between men armed with automatic rifles and machetes.

The region was hard hit by severe drought in the Horn of Africa last year, exacerbating tensions over land in the area, and sparking tit-for-tat cattle raids.