International observers in Algeria have endorsed the presidential election which was won by the incumbent, Abdelaziz Bouteflika.
Bouteflika's supporters celebrated before results were announced
A monitor from European security organisation the OSCE, Bruce George, said the result was clearly what the Algerian people wanted.
Mr Bouteflika was re-elected with 83% of votes cast, according to official results of Thursday's poll.
His main rival, former Prime Minister Ali Benflis, claimed "massive fraud".
Mr Benflis, who took just 8% of the votes, said he would appeal against the result.
"We do not recognise these results," he told the BBC. "There's been massive fraud nationwide - we'll be taking our complaints to the Constitutional Court".
Other candidates have also criticised the outcome.
'One of the best'
But Western diplomats in Algiers say the poll appears to be the fairest since multi-party politics was introduced in 1989.
Some 120 international observers monitored the poll.
International election observers said they saw no evidence of fraud
"I know there are criticisms," said election monitor Bruce George, of the Organization for Security and Cooperation in Europe. "But in my view this was one of the best conducted elections, not just in Algeria, but in Africa and much of the Arab world."
He was quoted by the Associated Press as saying that if there has been fraud it should be investigated, "and it's up to the complainants to identify it".
US President George W Bush congratulated Mr Bouteflika and "the Algerian people for their dedication to
building a democratic political system".
French President Jacques Chirac said the vote
"allowed the Algerian people to show its willingness to
move forward on the path of democratic pluralism".
As Mr Bouteflika got more than 50% of the votes, there was no need for a second round of voting.
During polling, Mr Benflis and two other candidates said their information showed that no candidate had received more than 50% of the votes.
The BBC's Heba Saleh in Algiers says that although Mr Bouteflika had been expected to win, the scale of the victory - almost 8.5m votes - came as a surprise.
Abdelaziz Bouteflika - incumbent - 83.49%
Ali Benflis - former prime minister - 7.93%
Saad Abdallah Djaballah - moderate Islamist party, El Islah - 4.84%
Said Sadi - Berber campaigner - 1.93%
Louisa Hanoune - first ever female contender - 1.16%
Ali Fawzi Rebain - Human rights campaigner - 0.64%
Many Algerians say they voted for Mr Bouteflika because he had brought security to their country, she says.
They approve of the amnesty he offered Islamic militants who surrendered and they appreciate his talk of national reconciliation.
Algeria, they argue, is not in the mood for any new experiments with an untested leader.
Sensing victory, Mr Bouteflika's supporters began celebrating soon after polls closed on Thursday and continued overnight.
During voting on Thursday, there were skirmishes in the Kabylie region between police and young Berbers, who blocked roads to polling stations to enforce a boycott.
Police reportedly used tear gas to disperse protesters in the small town of Freha near the regional capital, Tizi Ouzou.
The BBC's Mohamed Arezki Himeur in the town said there were no polling stations in some areas.
But residents said voting in Kabylie's second city, Bejaia, went ahead normally, the AFP news agency reported.
Berber activists want their Tamazight language to be given equal status to Arabic.