Iran's reformist and ultraconservative presidential candidates traded accusations Saturday over the country's economic crisis during the first pre-election debate broadcast live on television.

Iranians are set to elect a successor to President Hassan Rouhani on June 18 amid widespread discontent over a deep economic and social crisis caused by the reimposition of crippling sanctions after the US pulled out of the 2015 nuclear deal.

Iran's conservative-dominated Guardian Council approved seven candidates -- five ultraconservative and two reformists -- to run from a field of about 600 hopefuls.

Ultraconservative judiciary chief Ebrahim Raisi is widely seen as a favourite, after the Council disqualified moderate conservative Ali Larijani.

On Saturday, ultraconservative candidates called on reformist hopeful Abdolnasser Hemmati, who is the country's central bank governor, to take responsibility for the crisis, and accused him of seeking to defend the government's record.

"Mr Hemmati, your governance was catastrophic, you are sitting here as a representative of Mr Rouhani," said Mohsen Rezai, a former chief of Iran's Revolutionary Guards.

Rouhani is Iran's main architect of the 2015 nuclear agreement with world powers.

The accord has been on life support since then-US president Donald Trump unilaterally withdrew from it in 2018, and reimposed crippling sanctions.

An Iranian man watches the first presidential candidates' debate at a shop in Tehran on June 5, 2021. Iranians are set to elect a successor to President Hassan Rouhani on June 18
An Iranian man watches the first presidential candidates' debate at a shop in Tehran on June 5, 2021. Iranians are set to elect a successor to President Hassan Rouhani on June 18 AFP / -

Global powers have been meeting in Vienna since early April in a bid to revive the accord.

Reformist Hemmati instead took aim at his ultraconservative adversaries' economic plan, saying their pledges of massive direct financial aid were "unrealisable".

He also accused them of undermining Iran's international relations and preventing the country from benefiting from the nuclear deal.

Ultraconservative Raisi, who took 38 percent of the vote in the 2017 presidential election, avoided direct clashes with the reformists.

"Inflation is one of the serious problems people are facing today. The price of basic products has gone up considerably," he said, adding that the "dishonesty of certain officials" was one of the main worries of the Iranian people.

Iranian media has expressed concern in recent weeks about the risk of low voter turnout.

A record 57 percent of Iranians stayed away from parliamentary elections in February last year in which thousands of candidates, many of them moderates and reformists, were barred from running.

Further televised debates are due to be held on Tuesday and Saturday.