Iranians will vote for a new president on Friday following Ebrahim Raisi's death in a helicopter crash, choosing from a tightly controlled group of four candidates loyal to the supreme leader, at a time of growing public frustration.

While the election is unlikely to bring a major shift in the Islamic Republic's policies, the outcome could influence the succession to Ayatollah Ali Khamenei, Iran's 85-year-old supreme leader, in power for three-and-a-half decades.

Voter turnout has plunged over the past four years, with a mostly young population chafing at political and social restrictions.

Polls open at 8:00 am local time (0430 GMT) and close at 6:00 pm (1430 pm GMT), but are usually extended until as late as midnight. As ballots are counted manually, the final result is expected to be announced only in two days although initial figures may come out sooner.

If no candidate wins at least 50 percent plus one vote from all ballots cast including blank votes, a run-off round between the top two candidates is held on the first Friday after the election result is declared.

Three of the candidates are hardliners and one a low-profile comparative moderate, backed by the reformist faction that has largely been sidelined in Iran in recent years.

Critics of Iran's clerical rule say the low and declining turnout of recent elections shows the system's legitimacy has eroded. Just 48% of voters participated in the 2021 election that brought Raisi to power, and turnout hit a record low of 41% in a parliamentary election three months ago.

Bd pratidin English/Lutful Hoque