An Iranian woman casts her ballot at a polling station during elections in Tehran on Friday. AFP

Iranians voted on Friday in elections for parliament and a key clerical body, amid fears of a low turnout and with conservatives expected to tighten their grip on power.

Supreme leader Ayatollah Ali Khamenei, who has called for a strong turnout, was the first to cast his ballot. He voted at a polling station in central Tehran, state television reported.

The elections are the first in Iran since widespread protests erupted after the death in custody of Mahsa Amini, following her arrest for an alleged breach of the country's strict dress code for women.

Since the last elections, Iran has also been badly affected by international sanctions that have led to an economic crisis.

More than 61 million of Iran's 85 million people are eligible to vote for members of parliament as well as the clerics of the Assembly of Experts, which selects Iran's supreme leader.

There were fears of a low turnout, however, after a state TV poll found more than half of respondents were indifferent about the elections.

Iran's President Ebrahim Raisi arrives at a polling station to vote during elections in Tehran on Friday. AFP

"Suppose that I vote: what would it change?" asked a 21-year-old from Kurdistan province who gave her name only as Hanna, for fear of reprisals. "They (the elected officials) do not respect their promises."

Her comments were echoed by Hashem, a 32-year-old from the southwestern province of Khuzestan. "The problem with the elections is that people are not happy with this system because of the political and economic situation," he said.

Another voter, Moradiani from south Tehran, said she would heed Khamenei's call to vote.

"The leader said that participating in the elections is an obligation," she said, "just as it is obligatory for us to pray."

Polls closed at midnight (2030 GMT), after voting hours were extended several times during the day, the official IRNA news agency reported.

Local Fars news agency estimated the turnout to stand at "more than 40 percent".

"The plan to boycott the elections, designed by foreign enemies and their internal supporters, failed with the participation of around 25 million people," it said, without elaborating.

Agence France-Presse