The United States on Saturday said it was "disturbed by irregularities observed during voting" in Rwanda's election, which longtime President Paul Kagame won with nearly 99 percent of the vote.
The state department reiterated "long-standing concerns over the integrity of the vote-tabulation process."
Mr Kagame easily won a third term in office in what he had called "a formality." He faces another seven years leading the small East African nation which is much praised for its economic performance but criticized for its silencing of opponents.
Electoral authorities said Mr Kagame won 98.63 percent of the vote. Neither of his two challengers won a full percentage point.
The US also said it remains "concerned by the lack of transparency in determining the eligibility of prospective candidates," and it commended Rwanda's media for reporting on complaints of harassment of some opposition candidates.
Mr Kagame faced two challengers: Frank Habineza of the Democratic Green Party of Rwanda — the only permitted opposition party — and independent candidate and former journalist Philippe Mpayimana. Three potential candidates were disqualified for allegedly failing to fulfil requirements including collecting enough signatures.
Mpayimana received just 0.73 percent of the vote. Habineza received 0.47 percent.
"This election was criticized so much due to me continuing to be your leader, especially by people from outside the country because they oppose the will of Rwandans," the president told jubilant supporters on Saturday. "But Rwandans have shown that it was not manipulated by anyone but their own will."
Mr Kagame became the de facto leader of Rwanda and its 12 million people since, as a 36-year-old, his rebel army routed extremist Hutu forces who slaughtered an estimated 800,000 Tutsis and moderate Hutus and seized Kigali in 1994.
The country's politicians appointed him president in 2000. He was then elected in 2003 with 95 per cent of votes and again in 2010 with 93 per cent of votes.
The lanky former guerrilla fighter, now 59, is one of Africa's most divisive leaders, with some hailing him as a visionary while critics see a despot aiming to become one of the continent's presidents-for-life. He is credited with achieving a remarkable turnaround in his war-shattered nation, which now boasts annual economic growth of about seven per cent, is safe, clean and does not tolerate corruption. Rwanda also has the highest number of female politicians in the world.
However, human rights groups accuse his government of using state powers to silence any opposition - a charge the Rwandan authorities, including the president, deny.
But Mr Kagame's critics have ended up jailed, forced into exile or assassinated, and few Rwandans would dare to openly speak against him.
'A winning team'
Those who praise him, do so with adulation.
"He freed the country, he stabilised the country. Now we can walk anywhere day or night without problems," Jean Baptiste Rutayisire, a 54-year-old entrepreneur, said at a polling station in Kigali.
"He is an exceptional man. You don't change a winning team." But like many voters, Mr Rutayisire did not know the names of the other candidates.
In July, Mr Kagame told a campaign rally that "the day of the presidential elections will just be a formality."
A constitutional amendment in 2015 allows him to stay in power until 2034 if he wishes. The United States, a key ally of Rwanda, opposed the change to the constitution. Mr Kagame has accused some Western diplomats of meddling in the country's affairs.
Well over 90 percent of Rwanda's 6.9 million registered voters cast their ballots, according to the Rwanda Electoral Commission.
In the capital, Kigali, there had been little hint of the coming vote. Candidates had been barred from putting campaign posters in most public places, including schools and hospitals. The electoral commission vetted candidates' campaign messages, warning that their social media accounts could be blocked otherwise.
A report by Amnesty International last month said two decades of often deadly attacks on political opponents, journalists and rights activists created a "climate of fear" ahead of Rwanda's election,
Around the country Rwandans gathered to hear the results, with some celebrating an early win for Mr Kagame. At a gymnasium in the capital loud music blared and traditional dancers took to the floor to entertain several hundred people.
Despite facing an unwinnable battle against Mr Kagame in which opponents had only three weeks to campaign, Mr Habineza was upbeat after voting earlier.
"For the first time since 23 years an opposition party has been in the ballot," he said. Previously only independents and parties allied with Mr Kagame fielded candidates.