International sanctions against Iran over its nuclear programme are having an effect, but have not yet convinced Tehran to step back, Israel's deputy foreign minister said on Thursday.

"Iran is on the verge of bankruptcy because of the sanctions, and there are growing protests against the ayatollahs, but these sanctions have not dissuaded the regime in power in Tehran from pursuing its nuclear ambitions," Danny Ayalon told Israeli public radio.

Israel has warned it could launch pre-emptive strikes against Iranian nuclear facilities, arguing they mask a drive for a weapons capability that poses an existential threat to the Jewish state.

Iran insists its nuclear programme is for peaceful civilian energy and medical purposes only, but it has been slapped with progressively tougher sanctions by the international community.

Israeli officials have repeatedly voiced scepticism about the effectiveness of sanctions on Iran, with a rare public divide opening between the Jewish state and Washington about what should trigger military action against Tehran.

But Ayalon said "our position and that of the United States are getting closer," on the issue.

Later Thursday, Israeli Prime Minister Benjamin Netanyahu was expected to devote most of his address to the United Nations General Assembly to Iran's nuclear programme.

In a statement before his departure for New York, Netanyahu said he was "working in every way so that Iran will not have nuclear weapons."

"Israel is a modern and strong state thanks to the strength and talents of its citizens and to our faith in the justice of our cause," he said.

Israel has the Middle East's sole, if undeclared, nuclear arsenal.