Zimbabwe's elections received cautious approval Friday from two African observer missions despite allegations by the main challenger to President Robert Mugabe and a local monitoring group that the vote was heavily rigged.

Olusegun Obasanjo, head of the African Union 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. Wednesday's contentious vote has created 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, and asked election authorities to investigate reports that tens of thousands of eligible voters were turned away. Another poll monitoring group in Zimbabwe said as many as 1 million of the more than 6 million eligible voters were prevented from casting ballots.

``If 25 percent were not allowed, then, yes, the election is fatally flawed,'' said Obasanjo, a former Nigerian president.  His mission has 70 observers.

The head of the observer mission for the Southern African Development Community, a regional body, described the election as ``very free'' and ``very peaceful,'' but noted that there were some violations and a full analysis was still underway.

``The question of fairness is broad and you cannot answer it within one day,'' said Bernard Membe, who is also Tanzania's foreign minister. ``And so be sure that within 30 days, through our main report, the question of fairness may come.''

Prime Minister Morgan Tsvangirai, Mugabe's main opponent in the presidential vote, has declared the election ``null and void.''

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.

Full results on the presidential and parliament votes have been promised by Monday.

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.

``I have never seen an election that is perfect,'' he said. ``The process continues and we have to limit our comments.''

Aisha Abdullahi, the African Union's commissioner for political affairs, said observers reported that Zimbabwe had made improvements in the conduct of elections since the last violent and disputed elections in 2008 that led regional leaders to forge a shaky coalition between Mugabe and Tsvangirai, the former opposition leader.

But she said voters' lists this time were not made available in time for inspection and verification by voters, contesting parties and candidates. Public scrutiny of the voters' roll was vital, she said.

She said the electoral commission printed 8.7 million ballot papers for 6.4 million voters, or 35 percent above the number of registered voters against the international standard of 5 to 10 percent.

Observers said a significant number of ballot booklets had missing ballot papers and papers without serial numbers.

The late publicity on the location of voting stations just 48 hours before stations opened contributed also to the high number of voters who were turned away because they were not at correct polling sites.

Abdullahi said observers reported a high number of disabled, elderly or other ``assisted voters'' being helped to cast their ballots by polling officers who may have influenced them against their free will. In some outlying stations, one-quarter of voters were helped this way.

She said some AU observers are to remain in Zimbabwe until Aug. 14. (AP)