Supreme Guide of the Islamic Republic of Iran Ayatollah Ali Khamenei, early on Friday, cast his ballot at start of the nationwide polling that involves simultaneous presidential and municipal elections. State-run television quoted the bespectacled bearded top leader of the nation, as saying he would not reveal name of the candidate he had chosen to anyone, even to his family. He affirmed that the election is a great responsibility that warrants strict law-abidance and integrity and urged the people to come to the ballot stations early and abstain from delaying this to late hours of the process. Iran\'s presidential elections got underway throughout the nation early on Friday, in a race involving six contenders for the top post. Majority of the president-hopefuls are very close to the supreme guide, who enjoys substantial powers. The ballot stations opened at 8 a.m. (Iran local time) marking start of the crucial polling process, involving many of the estimated 50 million eligible voters. The 130,000 centers, located in the country\'s various provinces, are tentatively scheduled to close at 6 p.m. However, the interior minister may extend the 10-hour balloting in case many Iranians remained awaiting their turn to cast the vote after the scheduled closure of the centers. The contenders for the number-one post are Saeed Jalili, the secretary general of the higher national security council, the former chief of the council, Hassan Rohani, Tehran mayor Muhammad Ghalibuff, former foreign minister Ali Akbar Velayati, Muhammad Gharazi and Mohsen Rezaei. Some 300,000 security personnel have been charged with ensuring law and order, particularly at the ballot stations. These elections are of paramount significance, with a pile of issues that needs to be tackled at the local and external levels.