The U.S. State Department is expressing "serious concern" about a key referendum in Sudan next week to determine the political future of its war-torn Darfur region.
The April 11-13 vote was called to determine whether to unify the region's five states — a long-standing demand of rebels seeking greater autonomy from the Khartoum government.
A U.S. statement Saturday said that if the vote was held under current rules and conditions, it could not be considered a "credible expression" of voter preferences and would "undermine the peace process now under way" in the region.
Ethnic minority insurgents battling government forces since 2003 say ongoing fighting will intimidate potential voters and discourage them from casting ballots.
However, Sudan's President Omar al-Bashir — wanted by the International Criminal Court on war crimes charges — continues to insist conditions are stable enough to hold the referendum.
Analysts say the outcome will most likely favor the current five-state system, which critics say gives Khartoum greater control over the breakaway region.
Charges against Bashir stem from the 13-year conflict in Darfur, which the United Nations says has killed 300,000 people and driven 2.6 million others from their homes.
In the statement Saturday, State Department spokesman Mark Toner said lasting peace Sudan "will only be attained through a political process that addresses the underlying causes" of the Darfur conflict.
He also said peace would require "an inclusive and genuine national dialogue" that includes the participation of Darfuri groups and Sudanese representatives, and he warned that the upcoming vote "will contradict these key objectives."