DUSHANBE: Tajikistan voted Sunday in parliamentary elections expected to tighten the grip on power of long-serving strongman President Emomali Rakhmon and even introduce his son as a possible successor.

The election looks likely to boost the mandate of the ruling Democratic People's Party, which already holds 57 of the lower house of parliament's 63 seats, while sidelining their long-time rivals, the Islamic Renaissance Party.

Most attention has focused on Rakhmon's 23-year-old son Rustam Emomali -- a professional footballer with little experience -- who is running for a seat on Dushanbe's city council, considered a possible first step in a succession plan.

Rakhmon -- who has ruled Tajikistan for almost the entire post-Soviet period -- stood alongside his son at a Dushanbe polling station as he cast his ballot and called for fairness in a poll marked by a distinct lack of competition.

"Let us not break the law in today's election. This is an important political event for Tajikistan to promote economic and social life," he said.

"The more transparent and democratic the elections are, the higher Tajikistan's credibility will be on the world stage," Rakhmon added

Tajikistan, an impoverished Central Asian state which shares a vast and porous border with war-wracked Afghanistan, has never held an election judged free and fair by international observers.

The election comes at a time of heightened tension over concerns that the violence which has spread to the northern provinces of war-wracked Afghanistan could spill across the poorly guarded border separating the neighbours.

Tajik cooperation with US-led military operations against the Taliban and Al-Qaeda has many anxious about the possibility of reprisals, said Alexander Cooley, an expert on Central Asian security at Columbia University in New York.

"The concern seems increasingly justified. For example, last September two tankers that crossed into Afghanistan via Tajikistan were hijacked in Kunduz, soon after they crossed the Tajik border," he said.

"It is always possible that militants may target supply lines and convoys on the Afghan-Tajik border or even in Tajikistan itself."

Into this tense situation steps young Emomali, whose run for city council is widely seen as a first step towards a possible family succession, an idea very much in vogue among the region's authoritarian rulers.

But little is known about the young sportsman, apart from rumours that he enjoys racing expensive cars around the capital at night and grumbling that he rarely shows up for his current job in the investment ministry.

With its air of inevitability, the poll has generated little excitement, although the central election commission put turnout at 51.4 percent halfway through polling.

"The election results are known in advance -- a victory for the president's party," 58-year-old Salim, who declined to give his last name, told AFP.

"That means more seats in parliament for his party, which lobbies for the interests of the authorities," he added.

Polls opened on schedule at midnight GMT, and were due to close 12 hours later at 1200 GMT, with the first election results expected to begin trickling in from around the mountainous country at around 1500 GMT.