Six candidates are standing, including Smirnov, 70, who is hoping for a sixth term of five years in power and on Sunday cast his vote in the regional capital of Tiraspol.

Russia, which stations troops in the region has put its support behind a rival candidate, local parliament chairman Anatoly Kaminsky, RIA Novosti news agency reported.

Russia has fallen out with the current leadership of Transdniestr and has launched several corruption probes over alleged embezzlement of Russian funds allocated to the region as humanitarian aid.

The mainly Russian-speaking region split from Moldova in the early 1990s after a brief civil war, with support from Moscow. However it has not achieved international recognition and remains largely lawless.

By 1500 local time (1100 GMT), more than 44 percent of voters had casts their ballots, approaching the threshold of 50 percent required to make the polls valid, RIA Novosti reported.

Voting is due to close at 2200 Moscow time (1800 GMT), with 17 international observers monitoring, the agency reported. The region has 401,1993 registered voters.

The election comes as Moldova is gripped in a long-running political crisis that has prevented it from electing a president for four years.

Moldova and Trandniestr suspended talks five year ago, but resumed negotiations just two weeks ago.

The talks were held in November in Vilnius, Lituania, under the auspices of the OSCE, with the European Union and the United States acting as observers. They are due to continue in Ireland in February.

In a referendum conducted in 2007, 97 percent of voters in Trandniestr said they would prefer to be under Russian rule.