Iranians have headed to the polls in a snap election following the unexpected passing of former President Ebrahim Raiesi in a helicopter crash.

According to The Iran Project, polls opened at 8 a.m. local time (0430 GMT) on Friday. They close at 6:00 p.m. (1430 GMT), subject to extension by the interior ministry if necessary.

Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei cast his ballot at a polling station in Tehran just as the voting began.

"We recommend our dear people to take voting and participation in this important political test seriously and participate" in it, he said after voting.

"In order to prove the health and sincerity of the Islamic Republic's system, the presence of the people is necessary and obligatory," he said.