Veronique de Keyser, who headed a 130-member team, said names were missing from voter registries, election resources were not evenly spread to all parts of the vast country and there were cases of voter intimidation.

The five days of voting, which ended Thursday, were the first multiparty presidential, parliamentary and local elections in 24 years.

They were a key requirement of a 2005 peace deal that ended a 21-year civil war between the Sudan's predominantly Arab and Muslim north and rebels in the Christian-animist south. The war left 2 million people dead.

The EU mission concluded that key aspects of the election process were undermined.

"Although these elections paved the way for democratic progress, it is essential that the shortcomings are addressed," de Keyser told reporters in the capital, Khartoum.

"In addition to deficiencies in voter lists, week organization hindered voters' participation," she said. "I'm also concerned that polling was affected by intimidation and threats."

The EU mission had 130 observers at 13 percent of the country's polling stations.

Former U.S. President Jimmy Carter's election monitoring organization delivered a similar assessment Saturday.

"It is too early to offer a final, overall assessment, but it is obvious that the elections will fall short of international standards that are expected of advanced democracies," Carter said at a news conference.

"The people's expectations have not been met."