* Country borders Afghanistan
* Shaken by civil war in 1990s, after Soviet Union collapse
* Rakhmon has been in power since 1992
* Opposition accuses him of personality cult
By Roman Kozhevnikov and Dmitry Solovyov
DUSHANBE, Nov 6 (Reuters) - Tajik President Imomali Rakhmon, his only serious rival disqualified, headed for re-election on Wednesday in a Central Asian country beset by poverty and facing security threats from neighbouring Afghanistan.
Critics say Moscow-backed Rakhmon, 61, must tackle mounting social tension in the former Soviet republic where about half the 8 million population live in poverty 16 years after the end of a devastating civil war.
Tajikistan remains a poor country in a region riven by ethnic divisions. Conflicts have occurred across the border in Kyrgyzstan. Uzbekistan, courted by the West and Russia for its energy resources and strategic position, has suffered sporadic bombings and shootings authorities blame on Islamist militants.
The face of Rakhmon, in power since 1992, dominated the centre of Dushanbe on Wednesday, looking down from billboards. Young people voting for the first time were given bunches of flowers. Tajik music blared on loudspeakers.
"Our president is good, so we voted for him," said pensioner Zikiriyo Sharipov.
Housewife Nazira Karaboyeva said she saw Rakhmon as a guarantor of stability and "for everything to stay as good as it is right now".
There were no openly dissenting voices.
The former Soviet state farm head ran against five little-known, mainly loyal candidates. The one serious rival, a 65-year-old rights activist, said her backers had been obstructed in trying to gather the 210,000 signatures needed to run.
Rakhmon's press service declined comment on the accusation.
The West has not recognised a single election in Tajikistan to be free and fair. A delegation of the Organisation for Security and Cooperation in Europe, which monitored the election, is due to present its conclusions on Thursday.
Tens of thousands died in a 1992-1997 civil war after the Soviet Union collapsed. Fear of a return to conflict is strong.
Polls closed at 8 p.m. (1500 GMT), and first official results are expected early on Thursday.
Rakhmon, like other Central Asian leaders, could face security threats from Islamist militants in neighbouring Afghanistan after the planned withdrawal of U.S.-led forces in 2014. Tajikistan also lies on a heroin trafficking route from Afghanistan to Russia and Europe.
Rakhmon did not conduct an election campaign, relying on extensive media coverage of trips across the country where he was met by jubilant crowds reciting poetry glorifying him.
By barring moderate opposition candidate Oynihol Bobonazarova, secular authorities risk radicalising opposition.
Bobonazarova is backed by the Islamic Revival Party, Tajikistan's second-largest political force, and by the opposition Social Democratic Party.
Many of Rakhmon's opponents in the civil war won by his secular government are now in the Islamic Revival Party. But the opposition is weak and disparate, and there is official pressure on media and those accused of preaching radical Islam.
Bobonazarova said Rakhmon had developed a personality cult and people hid their true feelings.
"We have so many problems, and they (people) keep singing odes in his honour. They extol him, and later on they say terrible things about him," she told Reuters before the vote.
In October, Dushanbe ratified a deal with Moscow under which Russian soldiers will be deployed at a base in Tajikistan for three decades. In return, Tajik officials said, Rakhmon won a deal allowing some duty-free imports of oil products and agreement by Moscow not to get tougher on Tajik migrants.
Rakhmon has repeatedly voiced concerns that the spread of a militant form of Islam similar to that of the Taliban in Afghanistan could shatter the fragile peace in his country.
The Moscow-led Collective Security Treaty Organisation, which unites six former Soviet republics, said in September that it would provide "additional collective assistance" to Tajikistan to guard its border with Afghanistan after the pullout of most U.S.-led combat troops in 2014.