The African Union has canceled a delegation in the Democratic Republic of Congo on the country's disputed presidential elections after the Constitutional Court declared Felix Tshisekedi the winner, said a source of the UA on Sunday.
At a summit on Thursday, UA leaders cited "serious doubts" over electoral data and asked to delay the final results.
The European Union is in agreement with the evaluation of the UA, a spokesman said.
But the 16-nation Southern African development community congratulated Tshisekedi, a long-standing leader of the opposition, on Sunday for being elected president-elect and called for a peaceful handover of power.
The mission of the African Union in Kinshasa, led by the president of the UA Paul Kagame, the Rwandan president and the president of the AU Commission Moussa Faki of Chad, had been set for Monday.
South Africa urges "all parties" to accept the victory of the Tshisekedi RDC
South Africa congratulated Felix Tshisekedi on Sunday to become elected President of the Democratic Republic of the Congo following a ruling by the Constitutional Court, despite the African Union and the EU warning about the electoral outcome of the country.
"President Cyril Ramaphosa congratulated Felix Tshisekedi Tshilombo," the presidency said in a statement, asking "all parties and all parties in the DRC to respect the decision of the Constitutional Court".
"President Ramaphosa also congratulated the people of the DRC for conducting peaceful elections and praised them for putting a brake on and keeping calm when they waited for the Constitutional Court to decide," he added.
"Now that the Supreme Court in the land has governed, the entire population of the Congo and all the parties concerned are urged to accept the outcome of the Court and move on to consolidating democracy and preserving peace, stability and security".
Announcing the final results of the much-delayed survey, the High Court of the Democratic Republic of the Congo launched a challenge from runner-up Martin Fayulu in an announcement of the night.
He declared Tshisekedi the victor, paving the way for him to take the place of the historical leader of the country, Joseph Kabila, 47 years old.
The controversial result has raised fears of new bloodshed in the vast and unstable nation of Central Africa.