The United States on Friday voiced alarm over Guinea's plans to hold a constitutional referendum, which the opposition calls a ploy by President Alpha Conde to stay in power.
Secretary of State Mike Pompeo, who had urged Conde to respect democratic transitions of power when they met in Washington last year, said the United States was "concerned" by plans for the March 1 referendum and legislative elections.
"We question whether the process will be free, fair and transparent and accurately reflect the will of all eligible voters," Pompeo said in a statement.
"We urge all parties to engage in nonviolent civil dialogue," he said.
Pompeo called on authorities to allow peaceful demonstrations, while asking the opposition to refrain from violence, after at least 28 civilians and one security officer were killed in protests in the capital Conakry.
Conde, 81, was a longtime opposition figure who became the West African nation's first-ever elected president in 2010 on promises to fight corruption. He was re-elected in 2015.
But Conde has since been accused of sliding toward authoritarianism and has questioned the relevance of restricting the presidency to two terms.
While a draft constitution maintains the two-term limit, critics fear Conde could use the new text to reset the clock and allow himself two more mandates.