Olusegun Obasanjo, head of the African Union observer mission, said his monitors noted some apparent irregularities but that they did not constitute evidence of systematic tampering. Mugabe's supporters have rejected allegations of rigging and claimed victory, raising fears of a fresh uncertainty in a country long afflicted by division and economic turmoil.
"Yes, the election is free," Obasanjo said. He described the vote as credible unless any evidence to the contrary emerges.
"If 25 percent were not allowed, then, yes, the election is fatally flawed," said Obasanjo, a former Nigerian president. His mission has 70 observers.
Prime Minister Morgan Tsvangirai, Mugabe's main opponent in the presidential vote, has declared the election "null and void."
More From This Section
Official results announced by the election commission by Friday morning showed Mugabe's ZANU-PF capturing 54 of the 210 parliament seats and Tsvangirai's party winning 19 seats so far.
Obasanjo said voting itself was peaceful but the observers noted "incidences that could have been avoided and even tended to have breached the law."
Independent election monitors have alleged many people were unable to vote because of disorganized voters' lists and a chaotic program to register electors on those lists in the run-up to polling day.
Obasanjo said some apparent irregularities were made in error largely after funding for the vote was late in coming from the nation's depleted state coffers.