HARARE, Zimbabwe — The African Union (AU) says it is reserving its judgment on whether Zimbabwe's elections were systematically flawed until details of the disputed vote are clarified.

The head of the AU's 70-member observer mission, Olusegun Obasanjo, said Friday that voting was peaceful but that observers noted "incidences that could have been avoided and even tended to have breached the law."

The mission is asking election authorities in Zimbabwe to investigate reports that large numbers of eligible voters were turned away from polling stations in Wednesday's vote.

The party of President Robert Mugabe is claiming a landslide victory. His main challenger, Prime Minister Morgan Tsvangirai, has alleged massive rigging and declared the election "null and void."