Of the estimated 1.1 million refugees in Kenya, 735,800 are assisted by the UNHCR.
UNHCR provides services such as registration in urban areas and healthcare support to dispensaries that serve the displaced people.
He said the influx of refugees to Kenya from Somalia had slowed down after the military incursion into that country by Kenyan forces made movement difficult.
Data from the UNHCR shows that Kenya is hosting 623,000 refugees from Somalia.
More than 400,000 refugees live in Dadaab, the largest refugee camp in the world.
The notice to have all refugees in urban areas got to the Dadaab camp came at a time when there have been a series of explosions in Nairobi, particularly in Eastleigh area where most Somalia refugees live.
Kenyan forces have been dealing with increased influx of refugees on the Kenya-Somalia border where cases of terrorism have been rampant.
Various humanitarians organisation have also reported being overwhelmed by refugee influx adding that the order could further stretch their capacity to handle them.