US Secretary of State John Kerry Saturday denounced what he called "hysteria" over a final nuclear accord being discussed between world powers and Iran over its controversial nuclear programme.

"There's a lot of hysteria about this deal. People really need to look at the facts, and they need to look at the science behind those facts," Kerry told Israel's privately run Channel 10 Television in an interview.

Kerry said a final agreement due to be agreed by June 30 provides indefinite access to Iranian nuclear facilities.

"We will have inspectors in there every single day. That's not a 10-year deal. That's forever. There have to be inspections," he said.

"I say it again. We will not sign a deal that does not close off Iran's pathways to a bomb and that doesn't give us the confidence to all of our experts and global experts, that we will be able to know what Iran is doing and prevent them from getting a nuclear weapon."

On Wednesday, Iranian Foreign Minister Mohammad Javad Zarif told an audience at New York University that Tehran is willing to submit to the highest level of international transparency on its nuclear programme and wants to conclude a final accord as soon as possible.

If fully implemented, a deal will see Iran dramatically scale back its nuclear activities and submit those that remain to what US President Barack Obama has described the "most robust and intrusive inspections and transparency regime ever negotiated".

In return, the United States and five other major powers committed to lift certain sanctions that have caused the republic of 75 million people major economic pain by strangling its oil exports and financial system.

On April 15, Israel's Prime Minister Benjamin Netanyahu compared Israel's arch-foe Iran to Nazi Germany, and suggested that the lessons of World War II had not been learned.