President Bingu wa Mutharika of Malawi has rejected calls to step down after the deaths of 18 people in two days of anti-government riots.
Demonstrations were held across the country, despite an earlier court ruling banning the protests.
In an address to the nation, Mr Mutharika said the protesters were ''working for Satan'' and would be defeated.
The BBC reports the army has been deployed in the capital, Lilongwe, the biggest city, Blantyre, and Mzuzu in the north to bolster riot police.
Protesters accuse the president of plunging Malawi into its worst economic crisis since independence.
The government passed an austerity budget recently, raising taxes to reduce dependence on aid.
Malawi is one of the poorest countries in the world, with an estimated 75% of the population living on less than $US1 (60p) a day.