STORY: Iran on Thursday started registration of candidates for an early election next month following the death of President Ebrahim Raisi in a helicopter crash.

He was once seen as a possible successor to Supreme Leader Ayatollah Ali Khamenei, Iran's aging ultimate decision-maker.

Now Raisi's sudden death in mid-May has triggered a race among conservatives to influence the selection of Iran's next leader.

State media said former chief nuclear negotiator Saeed Jalili was the first heavy-weight hardliner to register.

Interim President Mohammad Mokhber is another name mentioned, as is former parliament speaker Ali Larijani.

Several low-key moderate politicians are also likely to enter the race.

After the five-day registration period, the Guardian Council, which oversees elections and legislation, will vet the contenders and publish a list of qualified candidates.

Moderate politicians have accused the hardline council of disqualifying rivals to hardline candidates, who are expected to dominate the upcoming race.

Turnout may be hit by restricted choice on the ballot and rising discontent over an array of political, social and economic crises.

Within Iran's complex mix of clerical rulers and elected officials, Khamenei has the final say on all state matters such as nuclear and foreign policies.

But the elected president will be in charge of tackling worsening economic hardship.