Saturday's vote was the third presidential election since the end of the West African country's brutal 11-year civil war that ended in 2002, and experts say it is a key test of how far the nation has come.
While local radio stations have begun airing unofficial results from some polling stations, the National Electoral Commission has yet to announce whether the vote will go to a second round.
The incumbent, President Ernest Bai Koroma, must garner 55% of the ballots cast or he will face his main opponent Julius Maada Bio in a second round of voting.
In issuing the European Union (EU) observer mission's preliminary results, chief observer Richard Howitt said on Monday it is up to the country's election body to make a decision on the when to announce the results. The body legally has up to 10 days following the election to declare its results.
"Clearly the National Electoral Commission will want to take sufficient time and care to ensure the accurate accounting of the vote but they will want to move as quickly as possible with the announcement of the results before any risks of instability or unrest," Howitt said.
Polling peaceful, orderly
Sierra Leone's chief elections officer Christiana Thorpe said that polling "was reported to be peaceful and orderly in almost all polling stations nationwide."
She, however, noted that polling was disrupted by a swarm of honey bees in ward 135 in the Kambia District.
"The polling station was automatically relocated and polling went on peacefully," she said.
The EU mission noted that there were isolated reports of the governing party distributing cash payments. While the mission was assured that the amount of money involved amounted to a local "handshake", Howitt said in one case there was "a significant amount of money involved".
There also was a report of one polling station where voters who presented identity cards were allowed to vote though they ultimately were not on the voter registry, Howitt said. The ballot boxes in question were under quarantine pending an investigation, he added.
The US-based Carter Center also said on Monday that Sierra Leone's vote had been "peaceful, orderly and transparent". Some polls opened late and in some cases there were shortages of election materials, the observers noted.
"These shortfalls were generally addressed by midday and they did not undermine the fundamental integrity of the electoral process," said former Zambian President Rupiah Banda who is with the Carter Center delegation.
Shedding its brutal past
The observer mission from the West African regional bloc Ecowas also noted a few isolated incidents, including the absence of back-up lighting which required party agents to improvise with cellphones and flashlights to enable counting in the dark.
Sierra Leone's presidential race has hinged on which candidate can best uplift this West African country trying to shed its past after a brutal 1991-2002 civil war.
A decade after the war's end, Sierra Leone remains one of the poorest countries in the world despite its diamonds and other riches. Several recent offshore oil discoveries, though, are raising hopes for economic development.
Most of the country's nearly six million people live on less than R11 a day, and it remains among the deadliest places in the world for women to give birth. Earlier this year, the capital was hard-hit by a cholera outbreak.
While Sierra Leone already had held two mostly peaceful votes since the war's end, experts said Saturday's vote would be a crucial test of whether those gains were irreversible.
Ban praises voters
UN Secretary General Ban Ki-moon praised Sierra Leonean voters for the "peaceful and largely orderly elections.
"The high voter turnout and the remarkable calm displayed by the country's citizens as they cast their votes are a clear manifestation of their desire for peace, democracy and development," said a statement released by his spokesperson.
The incumbent president, Koroma, has pointed to his accomplishments during his first term, pleading with voters in his campaign signs: "I Will Do More."
He faced eight opponents including leading opposition figure Julius Maada Bio, a retired brigadier general who calls himself the "father of democracy" after his brief three-month tenure at the country's helm in 1996. – Sapa-AP