The polls have closed in the energy-rich Central Asian state of Turkmenistan, where voters cast their ballots in a presidential election on Sunday.

According to Turkmen media, around 80 percent of the country's registered voters had cast their ballots shortly before polls closed at 1500 GMT. Preliminary results were expected to be released on Monday.

Incumbent leader Gurbanguli Berdymukhamedov attended a polling station in the capital, Ashgabat, with his father, son and grandson.

The 54-year-old was expected to easily win re-election, with his seven challengers seen as token candidates. Among them are government ministers and heads of state corporations, each of whom praised the president during the election campaign.

The Organization for Security and Cooperation in Europe decided not to send observers to monitor the vote after determining in a pre-election visit that due to a lack of real opposition candidates, their presence would not "add value" to the process.

The regional Commonwealth of Independent States did, meanwhile, send a team to oversee the elections.

After being elected with 89 percent of the vote in 2007, Berdymukhamedov began to gradually dismantle the personality cult surrounding the country's first post-Soviet leader, Saparmurat Niyazov, who died of a heart attack in 2006. He also introduced a series of reforms, which included the reopening of cinemas, theaters and research institutes. However, human rights groups have dismissed such moves a being largely cosmetic.

"Serious human rights violations such as torture and ill-treatment continue to be committed in detention facilities and severe restrictions remain on freedom of movement and expression, political activism, faith and many other fundamental rights," the human rights group Amnesty International said in a statement released on Friday.

Amnesty said repeated requests to visit the country had gone unanswered.

In terms of press freedom, an index compiled by Reporters Without Borders placed Turkmenistan in third-last place, ahead of only North Korea and Eritrea.

Almost 3 million people were registered to vote in Sunday's election in the former Soviet Republic, which holds about 4 percent of the world's natural gas reserves.

dfm, pfd/cmk (Reuters, AFP)