Iran is willing to submit to the highest level of international transparency on its nuclear program and wants to conclude a final accord as soon as possible, its foreign minister said Wednesday.

"The (UN nuclear agency) IAEA has seen everything and if you're looking for a smoking gun, you've got to wait a long, long, long time before you get one," Mohammad Javad Zarif told an audience at New York University.

Iran and the five permanent members of the UN Security Council -- Britain, China, France, Russia and the United States -- plus Germany have begun drafting a final nuclear accord due by June 30.

The agreement is intended to ensure the wholly peaceful nature of Iran's nuclear activities in exchange for the lifting of a raft of international sanctions imposed since 2006.

Tehran is ready to accept the "highest level of international transparency" available to members of the Nuclear Non-Proliferation Treaty, said Zarif.

"Iran is prepared, within an agreement, to accept the additional protocol and I think with that you will have all the transparency that you need."

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.

About the June 30 deadline, Zarif said: "No time deadline is sacrosanct."

"We want to finish this way before June 30," the minister said.

"We want to use every opportunity, including working around the clock starting next Monday, starting tomorrow actually here in New York, and then next Monday somewhere in Europe, to finalize all the elements."

Iran has fulfilled every detail of its undertaking, Zarif said, since an interim agreement in November 2013 eased the sanctions regime. But he criticized the United States for not doing the same.

"There is a lot to be desired in the way the United States, particularly the Treasury Department, has implemented its part," Zarif said.

"There were many incidents in which I took the heat when there was an apparent American, at least lack of good faith, in implementing its part of the deal when they increased or added new entities to the previous sanctions or similar measures."

An outline nuclear agreement reached on April 2 between Iran and six world powers, met with fierce opposition from US Republicans who say it would threaten America's security.

Obama called the agreement a "historic understanding" but Iran is concerned that the US Congress could introduce a bill to block a final accord.