Kazakhstan's President Nursultan Nazarbayev on Monday extended his grip on power in the oil-rich, ex-Soviet nation with 97.7 percent of ballots in an election slammed by Western observers as deeply flawed.

Nazarbayev, who has run the huge Central Asian country since before the breakup of the Soviet Union in 1991, improved his already eye-popping scores in previous elections to win a fifth term in power.

The Central Election Commission claimed a record turnout of 95.22 percent in Sunday's vote which was called a year ahead of schedule.

Western observers slammed the lack of choice in Kazakhstan's early presidential election in which the country's deeply marginalised opposition did not field a candidate.

The only two other contenders, figures widely seen as pro-government, scored less than three percent between them.

Reacting to Western criticism, the 74-year-old president issued a mock apology.

"I apologise that for super-democratic countries these figures are unacceptable," Nazarbayev, on course to reach three decades in power, told reporters.

"But I can't do anything about it. If I interfered, it would be undemocratic of me."

The Organization for Security and Cooperation in Europe (OSCE) slammed "significant restrictions" on freedom of expression and media freedom.

"Voters were not offered a genuine choice between political alternatives," said Cornelia Jonker, head of the OSCE monitoring mission.

The European Union echoed its criticism, urging the Kazakh authorities to "address these shortcomings, as well as other restrictions and irregularities observed by the OSCE".

- 'Wonderful country' -

Nazarbayev's latest win was celebrated across the country of 17 million with fireworks and flash mobs, with some saying people were genuinely pleased with the outcome.

"People say elections in our country are not real," said Abai Khuseinov, a student in Almaty. "So what is this happiness? Fake happiness?"  

A recent Ipsos MORI survey poll showed 91 percent of Kazakhs were either satisfied or very satisfied with his performance.

Rights activists said that support is the result of ignorance and propaganda, reinforced by crackdowns on the press and Internet.

"People believe that thanks to Nazarbayev we live in a wonderful country," said Dina Baidildayeva, a blogger and activist.

"People can't think critically because the education system is built in a way that oppresses independent thinking and encourages children to be submissive."

While AFP correspondents saw long queues snaking out of polling stations Sunday in a vote noticeable for its relaxed atmosphere, some voters complained at being asked to vote by their employers, a common practise across the former Soviet Union.

Foreign Minister Erlan Idrissov denied that such incidents were common.

"People came and voted voluntarily, not because they were forced to," he told AFP in an interview.

"We hold these elections and endeavour to make them honest and fair not in order to satisfy Vienna or Brussels."

Kazakhstan, which borders both Russia and China, has never held an election deemed free and fair by Western monitors.

- Tensions with Russia -

Russian President Vladimir Putin was among the first leaders to congratulate Nazarbayev on his victory amid heightened tensions against the backdrop of the Ukraine crisis.

Putin praised Nazarbayev's "decisive victory", saying it showed "broad support" for his policies, the Kremlin said.

Moscow's Ukraine policies have created a wave of concerns for Kazakhstan, which has a large Russian minority, and is tied to sanctions-struck Russia through their shared membership of the Eurasian Economic Union trade bloc.

While Nazarbayev was an early champion of Eurasian integration, Kazakhstan's enthusiasm appears to have waned because of the Ukraine crisis, with the country rejecting Putin's proposal of a single currency for the bloc.

Kazakhstan's producers have also been laying off workers as they struggle to compete with Russian imports made cheaper by the dramatic weakening of the sanctions-hit ruble.

Kazakhstan has banned a number of Russian foodstuffs, citing standards violations, and has also restricted imports of Russian fuel.

Moscow resorted to tit-for-tat measures this month.

-'Stable state'-

Nazarbayev said the election result boosted his plans to make Kazakhstan one of the world's 30 most developed economies.

"Without this level of general trust it would be difficult to work on realising such aims," he said, declaring the turnout to be proof of the desire of Kazakhstan's people "to live in a stable state."

Under his stewardship, the sprawling country has parlayed its energy resources and strategic location into influence, emerging from relative obscurity to host Iranian nuclear talks and chair the OSCE.

The son of a shepherd, Nazarbayev trained as an engineer before rising through the ranks of the Kazakh Communist Party to head it in 1989 before becoming president two years later.

In 2010, parliament granted Nazarbayev the status of "leader of the nation" --- Elbasy in Kazakh -- in a sign he may remain in charge of the country even if he steps down.

At the last election in 2011 Nazarbayev was credited with winning 95.5 percent of the vote.