Moroni - Voters in the Indian Ocean archipelago of the Comoros voted for a new president on Sunday from a crowded field of 25 candidates, with a struggling economy and poor infrastructure high on the agenda.Polling stations in the country of less than one million people officially opened at 04:00 GMT, although some were delayed by the late arrival of voting materials.By midday, no major incidents had been reported as some of the 159 000 voters on Grand Comore island cast their ballots in an election protected by several measures to combat voter fraud.Only voters on Grande Comore were eligible to vote in the first round of the election, in accordance with electoral rules that stipulate the president is chosen on a rotating basis from one of the archipelago's three main islands.Among those running for president are a former coup leader and the vice president.After the first round, the three top candidates will go into a nationwide run-off on April 10 that will decide the successor to President Ikililou Dhoinine.Dhoinine comes from Moheli, the smallest of the three main islands. The other island in the trio is Anjouan.The system of rotating candidates among islands was established in 2001 in a bid to usher in stability after more than 20 coups, or attempted coups, in the years following independence from France in 1975.Among the candidates leading the field are Vice President Mohamed Ali Soilihi, Grande Comore governor Mouigni Baraka and Azali Assoumani, a former coup leader and two-time former president.Athoumani Toioussi, an unemployed mother who was voting in the capital Moroni, on Grande Comore, said she would vote for Assoumani, despite his coup history."Yes, he came to power through a coup but it helped get the country out of chaos," Toioussi told AFP.Another voter, Houmadi Ahmedi, favoured Baraka saying "he gave learning materials to elementary school."Moinaecha Youssouf Djalali, a businesswoman, is the only female candidate in a country where the majority are Sunni Muslims.Avoiding 'double voting' Dhoinine's successful completion of his five-year term has been seen as a sign of growing stability in Comoros, though many candidates have expressed fears of electoral fraud when voting gets underway."Real efforts are being made by the election commission and international actors to ease any political or social tensions," said European Union representative Eduardo Campos Martins.In order to calm tensions, the electoral commission on Saturday agreed to a request from 20 candidates to ban proxy voting, seen as a possible source of fraud, "to preserve the peace".On Sunday, voters will also be forbidden from leaving Moroni or moving between villages unless they have an official pass "to avoid double voting", the interior ministry announced.The election is being monitored by dozens of African and international observers as well as a 425-person election monitoring platform established by local civil society groups to address voting glitches.Polling stations will close at 15:00 GMT, and early results are expected from Sunday night.