The United States on Tuesday denounced the forced resignation of Malian Prime Minister Cheick Modibo Diarra by members of the country's armed forces, calling it "a setback" for the West African nation's transition to normalcy.

"He was forced to resign and dissolve the cabinet. We condemn this act by the military junta and insist that it halt its continued interference in Malian political affairs government," State Department spokeswoman Victoria Nuland said at a regular news briefing.

The Malian prime minister resigned from office earlier in the day hours after he was arrested by soldiers supportive of ex-coup leader Amadou Sanogo.

The UN Security Council issued a statement condemning the arrest of Diarra and threatening "appropriate measures," including targeted sanctions, "against those who prevent the restoration of the constitutional order and take actions that undermine stability in Mali."

"We view this even as a setback for Mali's transition and its efforts to try to restore constitutional order and democratic government," Nuland said, calling for "free and fair" elections to be held as quickly as possible, preferably by April 23.

"A popularly elected government of Mali is critical to restoring that country's ability to control and defend its territory," she said.

"So that is a matter of extreme concern and it speaks to why we 've got to have a political solution in Mali going hand-in-hand with increased security," she added. "First and foremost, we need Sanogo and his brothers in arms to stay out of politics because it 's not helping."

The Economic Community of West African States produced a detailed plan last month for approval by the Security Council, under which 3,300 troops will be sent in to take back Mali's Islamist-dominated north lost after a March coup.