The United Nations human rights office has called on authorities in Malawi to investigate allegations of human rights violations by security forces during a crackdown on anti-government demonstrators last week.

A spokeswoman for the U.N. High Commissioner for Human Rights said Friday that the office has been following “with great concern” the reports of human rights violations resulting from that crackdown. She called on the government to stop its use of force on protesters and conduct transparent investigations of the alleged violations.

She also urged the government to stop the use of mass arrests and respect freedom of expression.

At least 18 people died last week when security forces in the country's three largest cities — — Mzuzu, Blantyre, and the capital, Lilongwe — clashed with demonstrators protesting the declining economy and the erosion of civil liberties.

A spokesman for President Bingu wa Mutharika has said the people who were killed were looters, not demonstrators.

Earlier this week, the United States put on hold a $350 million aid package to Malawi in response to the violence. The same day, some 100 people appeared in Malawi courts to face charges related to the demonstrations.