Voters cast ballots in the strategically important Central Asian nation of Tajikistan, neighbouring Afghanistan and China, in a presidential election in which incumbent Emomali Rakhmon is set to win his fourth seven-year term.

Voters headed to polling stations on Wednesday in the capital Dushanbe.

The five candidates standing against Rakhmon are virtual unknowns even inside the country, with next to no chance of victory.

Rakhmon, who has increased the number and length of his terms by revising the constitution through a referendum, won 79 percent of the vote in the previous election in 2006.

His next term must be his last, according to the constitution.

A turnout of at least 50 percent is required to make the election valid. Polls close at 8pm (15:00 GMT), and first official results are expected early on Thursday.

Harassment alleged

The potentially most significant rival candidate, female rights lawyer Oinikhol Bobonazarova of the moderate opposition Islamic Revival Party of Tajikistan, was unable to stand after narrowly failing to muster the signatures required to register her candidacy.

Bobonazarova gathered only 202,000 of the 210,000 signatures required, which equates to five percent of the electorate, a shortfall her party blamed on harassment from local authorities on its activists during the signature campaign.

Her party's spokesman confirmed that the Islamic Revival Party would not be taking part in the polls and would give its estimate after election day.

Another main opposition party, the Social Democratic Party, said it was boycotting the elections due to "violations of the constitution, organised falsifications and a lack of democracy and transparency."

The polls will be monitored by the Organisation for Security and Cooperation in Europe (OSCE).

Critics say Rakhmon, 61, faces mounting social tension in the Muslim state where about half of the eight million population live in poverty.

More than one million work abroad, sending money home to their families.

Potential security threats

Tajikistan could face security threats from armed groups in neighbouring Afghanistan after the planned withdrawal of US-led forces in 2014.

It also lies on a heroin-trafficking route from Afghanistan to Russia and Europe.

The Sunni Muslim country of eight million is one of the poorest among the ex-Soviet nations.



It depends on the remittances of the more than one million Tajiks working in Russia to make up nearly one-half of the nation's GDP.

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 US-led combat troops in 2014.

In October, Tajikistan ratified a deal with Russia 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.