An opposition presidential candidate in the Democratic Republic of Congo has filed an appeal in the constitutional court against last month's poll result.
Martin Fayulu insists he won the vote and has demanded a manual recount, but the electoral commission declared rival Felix Tshisekedi the winner.
Troops have deployed near Mr Fayulu's residence and outside the court.
He accuses Mr Tshisekedi, also an opposition candidate, of making a deal with outgoing President Joseph Kabila.
Mr Fayulu arrived on Saturday at the court.
Announcing the appeal, his lawyer Feli Ekombe said, quoted by AFP: "The petition demands the annulment of the results proclaiming Felix Tshisekedi president of the republic. It was introduced yesterday [Friday] and today we have come to get the receipts for this petition."
Mr Fayulu (second right) was given a receipt for his petition at the Supreme Court on Saturday
Speaking earlier to BBC Africa editor Fergal Keane, Mr Fayulu said: "I will do whatever is possible for me to do to get the truth because the Congolese want change."
On Saturday, Mr Fayulu repeated that the result did not reflect "the truth of the ballot boxes".
The electoral commission also said the pro-Kabila coalition had won a majority of parliamentary seats.
Several Western governments and the influential Roman Catholic Church in DR Congo have expressed surprise and concern at the declared results.
Mr Kabila has been in office for 18 years and the result, if confirmed, would create the first orderly transfer of power since independence from Belgium in 1960.
What does Fayulu say?
Dozens of Fayulu supporters had gathered outside his residence in the capital, Kinshasa, to chant slogans against Mr Kabila and Mr Tshisekedi.
However, they fled inside the building when the security forces arrived on Saturday, Reuters news agency reports.
Mr Fayulu admitted his court challenge would have little chance of success as the constitutional court was "composed of Kabila's people" but he said he did not want to give his opponents any chance to say he had not followed the law.
"Felix Tshisekedi has been nominated by Mr Kabila to perpetuate the Kabila regime. Because today the boss is Kabila," Mr Fayulu said.
Questions remain about the role of Joseph Kabila in the election result
"Mr Kabila cannot stay and make an arrangement with someone who will not have any power... Mr Tshisekedi knows himself that he did not win."
Mr Fayulu said he feared there would be violence if the electoral commission did not give the true figures "polling station by polling station" and that it was the right of all Congolese to demonstrate according to the law.
Have your say
More World Headlines
- Woman wakes up alone on dark, parked plane
- Jihadists kill 7 Chadian soldiers, local guard in ambush
- Man ordered to compensate ex-wife for 27 years of house chores
- US 'launched cyber-attack on Iran weapons systems'
- Ethiopia army chief shot dead in 'coup bid' attacks
- Ugandan activist to be prosecuted over president's mother
- Harry and Meghan split from William and Kate joint charity
- Gunmen kill dozens in 'terrorist' Mali attack
- Biden refuses to apologise for working with racist senators
- Nigeria condemns attack on its embassy in London
- Slavery reparations hearing ignites fiery debate in Congress
- $22,000 zoo funds stolen by robbers not eaten by gorilla - Nigeria governor
- South African MP punches man during alleged racist incident
- Jamal Khashoggi killing: Saudi crown prince 'should face investigation' - UN
- 70.8 million people displaced worldwide - UNHCR