Vladimir Putin has declared that he intends to seek re-election for another six-year term as Russian president.

Putin, 65, has been in power, either as president or prime minister, since 2000.

If, as expected, he contests and wins what would be a fourth presidential term in March, he would be eligible to serve another six years until 2024, when he turns 72.

Contest opinion polls show he will comfortably win the election, setting the stage for him to extend his dominance of Russia's political landscape into a third decade.

Vladimir Putin has declared that he intends to seek re-election as Russian president. The 65-year-old has been in power, either as president or prime minister, since 2000

If, as expected, Putin contests and wins what would be a fourth presidential term in March, he would be eligible to serve another six years until 2024, when he turns 72

'I will put forward my candidacy for the post of president of the Russian Federation,' Putin told an audience of workers at a car-making factory in the Volga city of Nizhny Novgorod.

Addressing the factory workers, Putin said he could not find a better place and a better moment to announce his candidacy.

Several hours earlier, he was asked about his intentions in Moscow and signalled that he would run but stopped short of declaring his bid.

Putin served two presidential terms in 2000-2008, then shifted into the prime minister's seat because of term limits, but continued calling the shots while his ally, Dmitry Medvedev, served as placeholder president.

Medvedev had the presidential term extended to six years and then stepped down to let Putin reclaim the presidency in 2012.

Putin's approval ratings that top 80 per cent make him certain to win an easy first round victory.

Putin served two presidential terms in 2000-2008, then shifted into the prime minister's seat because of term limits, but continued calling the shots while his ally, Dmitry Medvedev, served as placeholder president

Dmitry Medvedev (pictured) had the presidential term extended to six years and then stepped down to let Putin reclaim the presidency in 2012

He is lauded by allies as a father of the nation figure who has restored national pride and expanded Moscow's global clout with interventions in Syria and Ukraine.

His critics accuse him of overseeing a corrupt authoritarian system and of illegally annexing Ukraine's Crimea, a move that has isolated Russia.

The challenge for Putin is not other candidates - nobody looks capable of unseating him.

Instead, his toughest task will be to mobilise an electorate showing signs of apathy to ensure a high turnout which in the tightly-controlled limits of the Russian political system is seen to confer legitimacy.

The veterans of past campaigns - Communist chief Gennady Zyuganov, ultranationalist Vladimir Zhirinovsky and liberal leader Grigory Yavlinsky - all have declared their intention to run.

They will likely be joined by Ksenia Sobchak, a star TV host who is the daughter of late former St Petersburg Mayor Anatoly Sobchak, who was Putin's boss in the 1990s.

The most visible Putin foe, Alexei Navalny, is also considering running for president, even though a conviction he calls politically motivated bars him from joining the campaign

The most visible Putin foe, Alexei Navalny, also wants to run, even though a conviction he calls politically motivated bars him from joining the campaign.

He has organized a grassroots campaign and staged rallies across Russia to raise pressure on the Kremlin to let him register for the race.

While next year's election in March is devoid of real suspense about who will win, what follows is more unpredictable as attention will turn to what happens after Putin's final term - under the current constitution - ends.

There is no obvious successor, and many investors say the lack of a clear succession plan, and likely jockeying for position among Russian elites for dominance in the post-Putin era, is becoming the biggest political risk.

If re-elected next year, Putin will have to choose whether to leave Dmitry Medvedev as prime minister, or appoint someone else.

That decision will trigger a round of intrigue over the succession, as whoever holds the prime minister's post is often viewed as the president's heir apparent.