Iran is determined to end the "manufactured crisis" over its nuclear programme and drafting of a final deal with world powers, though hard, is progressing, Foreign Minister Mohammad Javad Zarif said Monday.

The remarks, on Zarif's official Twitter account, came two days after US Secretary of State John Kerry denounced what he said was "hysteria" from opponents of an agreement, which is due by June 30.

Zarif, Kerry and other diplomats from Iran and the P5+1 world powers (Britain, China, France, Russia and the United States plus Germany) say the deal would guarantee Iran's nuclear activities are peaceful.

"Drafting #IranDeal is moving forward. Hard work, and many brackets, remain. Determined to end this manufactured crisis & open new horizons," Zarif tweeted.

Iran has long asserted its nuclear programme is for peaceful energy purposes and that international concern about it seeking a nuclear bomb is misplaced.

An outline agreement between Iran and the P5+1 reached on April 2 in Switzerland after marathon talks met with fierce opposition from US Republicans who say it would threaten America's security.

But Zarif told an audience at New York University last week that Iran is willing to submit to the highest level of international transparency and wants to conclude a final accord as soon as possible.

If fully implemented, a deal would see Iran dramatically scale back its nuclear activities for at least 10 years along with other curbs in exchange for the lifting of UN, EU and US sanctions.

Iran's post-deal nuclear activities would be subject to the "most robust and intrusive inspections and transparency regime ever negotiated," US President Barack Obama has said.

However, there remains strong opposition in the US Congress and there are opponents in Tehran also who say Iran has already given up too much in the negotiations.

On April 15, Israeli 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.