About 28,000 people have fled from conflict-torn Central African Republic to neighbouring Cameroon since the start of this month, the UN refugee agency says.
"The new arrivals from CAR are living in appalling conditions. Most of them lack food and shelter," said Dan McNorton, spokesman for the UN high commissioner for refugees (UNHCR).
"Generous host communities have taken in many people, but they cannot share their homes and resources with everyone," he told reporters.
The influx, mainly of Muslims fleeing communal bloodshed, brings to 35,000 the total number of people who have fled across the border to Cameroon since a coup last March.
Even before the current crisis erupted when the mainly Muslim Seleka rebel coalition seized power last year, Cameroon was hosting 92,000 refugees from unrest-prone Central African Republic.
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They first started to arrive in 2006, fleeing growing attacks by rebels, militias and bandits.
McNorton said the growing number of refugees was driving up prices for food and other basic necessities such as soap and fuel.
The violence in Central African Republic spun out of control when rogue Seleka fighters began committing atrocities against the Christian majority.
The campaign of killings, rape and looting sparked revenge attacks by Christian vigilantes known as "anti-balaka" (anti-machete).
Despite the presence of French and African peacekeeping troops, violence continues in the country, and has already forced about a quarter of the population of 4.6 million people from their homes.
