Tashkent (AFP) - Uzbekistan's President Islam Karimov looked certain to claim victory in presidential polls Sunday after all three of the 77-year-old's challengers endorsed his bid to extend his 25-year-rule.

As polls closed in the Central Asian state, officials claimed that 91 per cent of the country's registered voters had cast their ballots.

Few had any doubt about the outcome of the election given the endorsement by Karimov's rivals.

In the era since independence, Karimov's presidency has been associated with lengthy presidential terms, landslide victories over low profile opponents and high turnouts at state elections.

Karimov, accompanied by his wife Tatyana Karimova, cast his ballot at midday in the weakly-contested vote in the country of more than 30 million, where voting began at 6:00 am (0100 GMT) as snow fell in the streets of the capital Tashkent.

Karimov, who won around 90 percent of the vote in 2007, is running for a five-year term following two seven-year stints.

Before those, the man who held onto his leadership position when the Soviet Union collapsed in 1991 extended his post-Soviet rule by referendum in 1996.

While exit polls are prohibited under Uzbek law, many voters in Tashkent told AFP they had voted for Karimov.

Burkhon, a 63-year municipal transport mechanic who declined to give his surname, cited periodic unrest in neighbouring Kyrgyzstan and Tajikistan, as well as the ongoing crisis in Ukraine, as reasons for casting his vote for the longtime strongman.

"We haven't had such bad things, thanks to Karimov, and we don't want them happening in the future," Burkhon told AFP.

Gulhayo Khujanova, an 18-year-old student casting her vote for the first time, told AFP: "I voted for our president, Islam Karimov. I am really satisfied with what he is doing for young people."

One voter, a taxi driver who requested anonymity, was undecided, saying: "I really wanted our respected President Karimov to retire, give the rule to someone younger and enjoy his happy retirement... But this is not going to happen, so I don't care now and I don't know who to vote for."

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- 'Stability' -

The ageing Karimov has contended with increasing rumours of illness and physical frailty but appeared healthy last weekend when dancing at celebrations to mark the beginning of spring.

He stressed the importance of stability during the low-key six-week campaign.

"What do Uzbek people need? We need peace and well-being," Karimov told the crowd.

On Wednesday he defended the need for "strong government", telling a small group of voters in comments aired by state media that otherwise "there will be chaos in society."

He added: "The time will come when we will give full freedom to our citizens, all human freedoms, and first and foremost, freedom of the media."

Karimov has continually warned of the danger posed by Islamic radicals based in Afghanistan, some of whom are ethnic Uzbeks.

"If we retain stability in Uzbekistan, we secure order in the entire Central Asian region," Rafik Sayfullin, a political analyst based in Tashkent, told AFP. "Let these elections pass normally so that we can keep the same team."

Strategically located Uzbekistan provided support to the US-led military operation in its southern neighbour Afghanistan and maintains close ties with both Russia and China.

More than 300 international observers from 43 different countries are monitoring the vote. The Organisation for Security and Cooperation in Europe (OSCE) is expected to issue its assessment of the ballot on Monday.

The presidential vote will complete a political cycle for the country after parliamentary elections -- which also saw a recorded turnout of over 90% -- took place in December.

Uzbek expatriates voted in a number of different countries where Uzbekistan has diplomatic representation, including Russia, where more than two million Uzbek migrant labourers live, according to the Federal Migration Service.