The reports from residents of Mary Province to RFE/RL were the latest in growing evidence that Turkmen officials are seeking to manipulate balloting in the March 12 vote, in which Berdymukhammedov is not running for reelection.

The snap election in the tightly controlled Central Asian country is widely seen just a formality to transfer power from Berdymukhammedov to his son, Serdar.

"All [state] employees were strictly ordered by the authorities to cast their ballots or March 10 or 11. Those who can't come to [early voting] must explain the reason to the authorities in written form," one resident of Mary city told RFE/RL on March 10.

Residents spoke to RFE/RL on condition of anonymity due to fear of prosecution or retaliation by the authoritarian government that has long tolerated no dissent.

Another Mary resident said that local officials had told people to "vote for Serdar, the son of our president."

Election workers have been instructed that they must help voters to find Berdymukhammedov's name among the total of nine candidates on the ballot papers, he added.

No election in Turkmenistan has been deemed free and fair by Western election monitors.

Gurbanguly Berdymukhammedov took over as president in 2006 after the death of the long-ruling, idiosyncratic president, Saparmurat Niyazov.

Observers had initially hoped that Berdymukhammedov might undo some of Niyazov's excesses, and open up the gas-rich country to more outside investment and foreign trade.

But Berdymukhammedov has imposed his own brand of autocratic rule.

In February, Berdymukhammedov, 65, announced that he intended to step aside to allow power to be turned over to "young leaders." The following day, parliament set the date for an early presidential election.

Serdar Berdymukhammedov, 40, is expected to easily win the election. Eight other contenders are viewed as token candidates to make the vote look like a genuine race.

In recent days, local officials and public sector employees have been going door-to-door to distribute invites for voters to take part in the election.

One Ashgabat resident told RFE/RL that, "those who distributed the papers, also told each voter that they must vote for Serdar Berdymukhammedov."

As part of his election campaign, Serdar has made several trips to the provinces amid tight security in recent days.

RFE/RL correspondents reported that the streets on the route of his visit had been paved and reconstructed, and new trees were planted along the way.

Should he succeed his father, Serdar would take over one of the most isolated and impoverished states in Central Asia, despite its vast natural-gas resources.