The sometimes chaotic situation in the country's first election in 16 years began with late opening of some polling stations and a shortage of ballots, particularly in the overcrowded capital of Luanda, the BBC reported Saturday.

Angola is holding its first free elections since the 1992 conclusion of civil war. Some opposition leaders called for an election do-over, suggesting the current process favors the ruling MPLA party of President Jose Eduardo dos Santos.

Unita Party leader Isaias Samakuva said Saturday that disorganization had caused the system to collapse. "At this stage, nobody knows what percentage of the electorate was present at polling stations," he told the BBC.

"We need to make this process credible -- credible not only to the Angolans themselves but to the international community as well," Samakuva said.

Luisa Morgantini, head of the European Union observer mission in Angola, expressed concern about the level of disorganization at the start of voting, but she told the British broadcaster that the situation improved as the day went on.