Official returns showed that President Nazarbayev won 91.01% of votes cast, securing another seven-year term at the head of the giant oil-rich state in Central Asia that he has led since the Soviet era.
But on Monday the Organisation for Security and Co-operation in Europe (OSCE) said the election on Sunday failed to meet international standards, citing ballot-stuffing, multiple voting, interference, media bias and intimidation.
In the pre-election campaign there was "limited possibility for a meaningful competition", the OSCE said in the capital, Astana.
After polling, the counting of ballots was "viewed as bad or very bad in one out of four counts observed".
Kazakhstan's election chief admitted shortcomings but said they had not affected the result.
Nazarbayev, whose 16-year rule has transformed this former Soviet backwater into an emerging world oil power, celebrated victory with 4000 supporters in Astana.
"The people of Kazakhstan won. You saw that the people voted for stability. This is not about revolution"
President of Kazakhstan
"The people of Kazakhstan won," he told cheering activists in yellow campaign shirts and caps. "You saw that the people voted for stability. This is not about revolution."
Nazarbayev also reached out to opponents, saying: "We will listen to them and work with them."
But Zharmakhan Tuyakbai, the main opposition candidate who won just 6.64% of votes, according to official results, spoke of impending dictatorship and called for the results to be annulled.
"The authoritarian regime of Nazarbayev is taking a totalitarian turn," he said in the city of Almaty.
"We will take all legal measures to protest the official results of the voting and will press for this election to be declared invalid."
According to officials, Alikhan Baimenov, the former labour minister, came third with 1.65%, then Yerasyl Abilkasymov of the People's Communist Party with 0.38%, and Mels Yeleusizov, an envirnonmentalist, with 0.32%.
Tuyakbai's spokesman, reacted with sarcasm. "I can only regret that Nazarbayev wasn't given 120 or 150%," he told AFP.
Zharmakhan Tuyakbai called for
the results to be annulled
Sarimov said voter lists had been falsified and the official turnout of about 77% artificially inflated.
However, the opposition has so far indicated that it will abide by a law banning street demonstrations in the immediate aftermath of the election. Tuyakbai said he would decide about protests according to the "situation".
Kazakhstan is the most prosper-
ous state in Central Asia
About 1600 observers monitored the election, including 465 from the OSCE, of which Kazakhstan is a member.
Bruce George, the OSCE observers' co-ordinator, said that "regrettably, despite some efforts which were undertaken to improve the process, the authorities did not exhibit sufficient political will to hold a genuinely good election".
Onalysn Zhumabekov, chairman of the Central Election Commission, described the OSCE criticism as generally "objective, but certain conclusions we don't agree with". He said the election had been "a big step forward".