The United States has strongly criticized Congo's recent presidential election and is refusing to say if it recognizes President Joseph Kabila as the winner.
State Department spokeswoman Victoria Nuland says the elections were "seriously flawed, lacked transparency and did not measure up to the democratic gains" seen in recent African elections.
Nuland said Wednesday it was unclear if the irregularities changed the outcome of the vote. She called for Congo to review the election and offered U.S. assistance.
Her comments come amid increased questioning of Kabila's November re-election.
Kabila was declared the winner with 49 percent of the vote. But the United Nations and Congo's influential clergy have raised concerns.
Nuland says all parties should act responsibly and refrain from violence.