Mr Mende said the AU delegation was welcome, but that the post-election process would remain unchanged.
Provisional results announced last week showed a shock victory for opposition leader Felix Tshisekedi. But Mr Fayulu requested a recount, saying he had won with over 60 percent of the vote and that Mr Tshisekedi was announced victor only after striking a deal with outgoing President Joseph Kabila.
Congo’s influential Catholic Church said the official results were inconsistent with its own tallies. Three diplomats briefed on the Church’s findings said they pointed to a clear victory for Mr Fayulu, a former Exxon Mobil country manager.
Both Mr Kabila and Mr Tshisekedi’s camps have denied any such manoeuvre. They have also denied accusations of fraud.
But the AU statement heaps more pressure on Kinshasa to address what independent monitors described as serious flaws in the process including faulty balloting machines and polling stations at which many were unable to vote.
An AU endorsement of the result is crucial for the legitimacy of the next president.
Congo, a vast and volatile country of 80 million people sprawling across central Africa, is the world’s leading miner of cobalt, used in electric car batteries and mobile phones, and Africa’s biggest copper producer.