Kenya Red Cross Society public relations officer Titus Mung'ou said up to 9,000 in one border area have left the border region following an increased Kenyan military presence, the U.N. Integrated Regional Information Networks said Friday.

"At least 1,500 families (9,000 people) have left Elwak (an area in Mandera) and its environs," Mung'ou said.

Mohamed Issack Dualle of the Rural Agency for Community Development and Assistance said an exact number of residents fleeing the border is difficult to ascertain due to the area's volatile situation.

Tension has been high along the two countries' borders during the last few weeks since suspected Somali gunmen were accused of kidnapping two nuns.

IRIN said the armed men were also accused of hijacking four vehicles in the area, leading to an increased border security presence by Kenyan forces.