Martin Fayulu restated his allegation that the vote result had been rigged, and suggested "holding the elections again within six months".
KINSHASA - The runner-up in DR Congo's presidential elections said he would appeal to the Constitutional Court for a recount as his bloc claimed he won the poll with 61 percent of the vote.
"We will go to the Constitutional Court on Saturday... (to demand) a recount of the vote," Martin Fayulu told a rally of his supporters.
Provisional results released on Thursday declared Felix Tshisekedi victor with 38.57 percent of the vote, just ahead of Fayulu with 34.8 percent.
The declared result was a surprise to many.
The few pre-election opinion polls had shown Fayulu to be clear favourite.
Fayulu's bloc on Friday said he was the true victor, claiming he had garnered 61 percent of the vote.
Democratic Republic of Congo has been in the grip of two-year-old political turbulence, triggered by President Joseph Kabila's refusal to step down when his two-term constitutional limit expired at the end of 2016.
Elections for his successor were delayed three times before finally taking place on December 30.