* Former maths teacher wins 62.7 pct of votes
* Residents celebrate in the streets of Bangui
* Unstable country seeks to end three years of strife (Adds reaction from the street, details throughout)
By Crispin Dembassa-Kette
BANGUI, Feb 20 (Reuters) - Former Central African Republic prime minister Faustin-Archange Touadera has won a presidential run-off, the electoral commission said on Saturday, in what was widely seen as a step towards reconciliation after years of violent turmoil.
Crowds sang and danced into the night in the streets of the capital Bangui, where many people have been killed during three years of inter-communal strife.
"It's the central African people who have won tonight," said Max Farafei, a 32-year-old motorcycle taxi driver. "Now we all need to rally behind (Touadera) to rebuild the country."
Touadera, 58, a former mathematics professor who campaigned against corruption, won 62.71 percent of votes cast in the Feb. 14 election, according to initial results announced by National Elections Authority (ANE) president Marie-Madeleine Nkouet.
Anicet-Georges Dologuele, also a former prime minister, won 37.29 percent, reversing the two rivals' rankings from the first round. Dologuele said he would accept the results, despite what he called "massive fraud" in the second round.
"For the sake of peace, I choose to respect the provisional results published by the ANE and to renounce an appeal to the constitutional court ... and to recognise Faustin Archange Touadera as the leader of all central Africans," he told reporters at his home shortly after the results were released.
Touadera's spokesman called for calm and asked the country's population of 5 million to accompany the new leader in his pursuit of "reconciliation and recovery".
Turnout in the vote was about 61 percent, the ANE said.
Central African Republic, one of the world's most chronically unstable countries, suffered the worst crisis in its history in early 2013 when mainly Muslim Seleka fighters toppled president Francois Bozize.
Christian militias responded to Seleka abuses by attacking the Muslim minority. A fifth of the population have fled their homes, either internally or abroad, to escape the violence, leaving the impoverished country divided along ethnic and religious lines.
The head of the African Union observer mission Souleymane Ndene Ndiaye on Saturday praised the election for its "calm, serenity and transparence".
But he noted logistical problems that led to the late opening of some polling stations. He recommended more funds be made available for the ANE to rectify problems with the electoral register.
The presidency of former colonial power France congratulated Touadera on his victory and pledged support for his forthcoming mandate.
The election results must be certified by the Constitutional Court within eight days to become final.
In January, local authorities cancelled the result of a legislative election held at the same time as the first round of the presidential vote in December, citing irregularities. a new government is in place, France is expected to resume a planned withdrawal of the remaining 900 of a force of troops it sent to the country during its turmoil. An 11,000-strong U.N. peacekeeping mission of other nationalities will remain in place.