The government of Malawi now says at least 18 people have been killed during clashes between police and anti-government protesters that began Wednesday.

Malawi's health ministry raised the death toll Thursday, soon after President Bingu wa Mutharika appealed for calm in a nationwide radio address.

The president said he is willing to sit down and talk with opponents.

Violent protests erupted Wednesday in the country's three largest cities — Blantyre, Mzuzu, and the capital, Lilongwe. Witnesses say rioters looted shops and set fires during the protests, and that police fired tear gas.

Demonstrators are protesting fuel shortages, rising prices and eroding civil liberties in the southern African country.

President Mutharika also has been criticized for his handling of a diplomatic disagreement that prompted Britain to cut economic aid to its former colony.

The dispute began after Mr. Mutharika deported Britain's envoy for describing the president in a leaked cable as “autocratic and intolerant.”

Pop star Madonna, who has adopted two children from Malawi and runs charities there, said in a statement she is deeply concerned about the violence. She said the country must find a peaceful solution to its problems so donors are confident their money will be used efficiently.