"As of 10 August 2012, the complex emergency in Mali had displaced an estimated 435 624 people," the Office for the Co-ordination of Humanitarian Affairs (OCHA) said.
"Of these, 261 624 refugees from Mali have registered with the United Nations High Commissioner for Refugees in neighbouring countries, and 174 000 are internally displaced."
Since a military coup on 22 March which toppled its president, Mali has fallen prey to hardline armed Islamist groups linked to al-Qaeda's north African branch Aqim who have taken control of a number of towns and villages.
According to OCHA, the worst affected region is Mali's vast desert north, where 105 000 people have fled fighting in the cities of Timbuktu, Kidal and Gao.
About 32 500 people have been displaced from the central city of Mopti and the rest from southern regions.
The Islamist groups have imposed strict sharia, prompting outrage in recent weeks by stoning an unmarried couple to death and cutting off the hand of a thief. They are also accused of recruiting child soldiers to their ranks.
Risk of famine
In the fabled city of Timbuktu they destroyed ancient World Heritage shrines, declaring them "haram", or forbidden by Islam.
OCHA's report also highlighted the health and food security crises wracking the country, including an outbreak of cholera near Gao in early July which has killed 11 people. About 140 cases have been reported.
Mali's location in the Sahel region, a semi-arid belt crossing the north of Africa, also exposes it to a risk of famine, says the report.
The Sahel is battling a severe food crisis after failed harvests last year that have left millions hungry. The conflict in Mali has placed even greater strain on food resources in the region.
The Food and Agriculture Organisation warned that "emergency food assistance must be provided to 4.6 million people" in Mali, which has a population of 14.5 million.
So far, the UN's World Food Programme has reached 360 000 people in southern Mali, OCHA's report said, and over 148 000 people in the north.
Finally, a plague of locusts in northern Mali is now spreading, warned the report, threatening agricultural production.