Conflicts over water and pasture are common in this barren region

The BBC's Bashkash Jugsodaay said some 5,000 members of the Garre clan, targeted in the raid by 80 Murule militiamen, have fled to El Wak town.

Since December some 50 people, mainly women and children, have died in violence in Mandera district.

A severe drought has led to competition for control of water and pastures.

Tension high

"We have boosted security and patrols along the areas that we think are vulnerable to revenge attacks," Gabriel Ndolo, a police commander in the area, told AFP news agency.

The 80 heavily armed men involved in the attack on the village have crossed over the border to neighbouring Somalia.

Security along the border has been tightened up and helicopters have been flying over the area, our correspondent says.

Some Murule families - up to 2,000 people, fearing a revenge attack, have also been fleeing their home areas to the towns of Mandera and Fino.

Nobel Peace Prize winner Wangari Maathai, Kenya's deputy environment minister, said in January she was ready to use her influence to reconcile the warring clans.

But our correspondent in the region says there has been little evidence so far of government efforts to resolve the dispute.

The communities grazing their livestock are scattered over a large area and police find it difficult to monitor, he says.