Moscow/Baku, Azerbaijan - President Ilham Aliyev is all but set to maintain his rule over post-Soviet Azerbaijan in Wednesday's elections as Russia and US continue to compete for his favour in the oil-rich Caspian state.

With Aliyev's only real opposition boycotting the vote, it is a forgone conclusion that the son of Azerbaijan's former strongman leader will be handed a five-year extension to 35 years of dynastic rule over the Caspian state.

Ten per cent of the country's 4.8 million voters in the principally Muslim nation neighboring Iran had cast their ballot two hours after polls opened at 8:00 am (0300 GMT), OSCE election monitors said. Polls were due to close at 7:00 pm (1400 GMT).

With no doubt about the outcome, the only question is whether Aliyev will be able to keep up his balancing act between Moscow and Washington's increasingly spiky energy interests after Russia's war with US ally Georgia in August upped the ante.

Azerbaijan is key to Washington's policy of securing Caspian Sea oil and gas through the Baku-Tbilisi-Ceyhan pipeline, bypassing Russia.

US Vice President Dick Cheney spent nearly three times as long on a visit to Baku last month as with other allies in the region.

Yet even before the war in Georgia, Russian President Dmitry Medvedev made for Baku to lobby for energy monopoly Gazprom to win a contract that would kill US-sponsored plans for the Nabucco pipeline, a new direct link from Europe to the Caspian basin's energy wealth.

Azerbaijan's oil riches have yielded one of the world's fastest- growing economies, with Aliyev reaping praise for infrastructure projects amid an astounding growth rate of over 34 per cent in 2006 - the latest year to provide statistics - that have been felt by all.

The six contestants joining him in Wednesday's ballot are seen as mere place cards after the only opposition candidates who could have provided a ghost of a challenges declared a boycott of the vote.

Pre-election debating, which went ahead without Aliyev, barely dented state television coverage of the national leader, and pollsters have reported widespread apathy in the face of the vote.

The OSCE's election observation mission to Baku said in a report this week that the "perceived lack of genuine competition" had dulled public interest.

Aliyev has favoured the West's energy interests in recent years while remaining on neutral terms with Moscow, but the fight over Georgia's separatist regions two months ago could force a shake up.

Azerbaijan is locked in its own frozen conflict with neighbouring Armenia with which it fought a bloody war in the early 1990s over Nagorno-Karabakh, an ethnically Armenian enclave that has remained under Yerevan's control since a 1994 ceasefire.

Analysts say Russia's venture into Georgia could not but raise the question of whether Moscow, a traditional ally of Armenia's, would intervene if tensions to protect its interests in another area.

For now, Russia has become the primary broker alongside regional power Turkey in a new round of negotiations to resolve the conflict.

A thousand international observers were watching the vote Wednesday, including near 400 from the OSCE, which will publish its assessment Thursday. (dpa)