KHARTOUM - Voting centres opened on Sunday in Sudan for the country's first multi-party elections in 24 years that is being marred by opposition boycotts and Western criticism. Logistical preparations are a key aspect in Sudan's election, in which 16 million people are registered to vote for a president as well as parliamentary and state representatives. South Sudanese will also vote for the leader of their autonomous regional government. Sixteen airplanes, 16 helicopters and more than 2,000 vehicles have been mobilised in the past two weeks to transport ballot boxes around the country. Related article: Low tech to the fore in Sudan campaigning "I hope that it will be completely compatible with international standards, and safe and free and fair, and that the decision of individual voters will be expressed freely without intimidation," said US former president Jimmy Carter whose Carter Centre is monitoring the three-day vote. These are "very troubled potential times (and) we hope it will be safe and free," Carter said. But the election has been marred by opposition boycotts. "We know there is no perfect election in the world, this is not an exception," said Abdullah Ahmed Abdullah, vice chairman of the national electoral commission. Carter said on Friday that he expected polling to proceed without major hurdles, although some delays could be expected in more remote areas. "We see no reasons for any concern except on a few isolated stations way out," said the former US leader. Voting materials "may get there a bit late, but they will have three days at least in which to vote," he told reporters in the capital. Related article: Carter hopes vote will meet 'international standards' In the run-up to the elections, opposition parties accused Beshir's ruling National Congress of fraud, particularly when the contract for ballot papers was given to a state-owned printer arousing suspicions of potential ballot stuffing.