Central African Republic President Catherine Samba-Panza has said she will "go to war" with Christian militias who are slaughtering Muslims.
She said the militias, called anti-balaka, had "lost their sense of mission" and had become "the ones who kill, who pillage, who are violent".
The militias claim to be taking revenge for atrocities by Muslims last year.
Tens of thousands of Muslims have fled into Cameroon and Chad and many more are living in camps inside CAR.
Amnesty International has described the situation as "ethnic cleansing".
But Ms Samba-Panza rejected that label and characterised the violence as a "security problem".
"They think that because I'm a woman, I'm weak. But now the anti-balaka who want to kill will themselves be hunted," she said in a speech.
Many of the Muslims who have fled were traders or involved in the food business.
Their absence has sparked a collapse in food distribution and worsened a humanitarian crisis.
Witnesses say dozens of dusty stalls at one market in the capital Bangui stand empty.
The only meat available is a small amount of pork from locally reared pigs.
The UN's World Food Programme has started a massive month-long airlift of food into CAR from Cameroon, with the first flight arriving on Wednesday.
A total of 1,800 tonnes of cereal will be delivered in the coming weeks, but the WFP says almost 10 times that amount will be needed.
It says about 1.3 million people - a quarter of the population - need food aid.
This phase of CAR's troubles began when largely Muslim Seleka rebels stormed through the country last year.
They toppled the government in March and installed their leader as interim president.
He stepped down last month after failing to quell communal violence, and Ms Samba-Panza was chosen to lead the country to an election.
Some 7,000 troops - from France and African countries - have been mandated by the UN to help restore order.
But so far they have failed to stop the unrest, which has intensified since the Seleka leader stood down as president.
Several Muslims have been brutally killed and their bodies mutilated in the streets of the capital Bangui.
CAR is rich in gold, diamonds and other natural resources but decades of unrest and mismanagement have left most of its people stuck in poverty.