Secretary of State Mike Pompeo has issued a steep list of demands that he said should be included in a nuclear treaty with Iran to replace the Obama-era deal, threatening "the strongest sanctions in history" if Iran doesn't change course.

Key points: Mike Pompeo gives first major speech as Secretary of State and threatens "toughest sanctions in history" on Iran

Mike Pompeo gives first major speech as Secretary of State and threatens "toughest sanctions in history" on Iran Submits 12 demands to the Middle East nation which would ensure it "has no possible path to a nuclear weapon"

Submits 12 demands to the Middle East nation which would ensure it "has no possible path to a nuclear weapon" Mr Pompeo warns punishment against European businesses which continue to trade with Iran

Following President Donald Trump's withdrawal from the deal, the United States will ensure "Iran has no possible path to a nuclear weapon, ever," Mr Pompeo said.

As he called for a better agreement to constrain Iran's activities, he said the US would "apply unprecedented financial pressure" to bring Tehran back to the table.

"These will end up being the strongest sanctions in history by the time we are complete," Mr Pompeo said at the conservative Heritage Foundation, his first major policy speech since taking over as top diplomat.

The Secretary of State's list of 12 requirements included many that Iran is highly unlikely to consider.

Mike Pompeo has backed president Donald Trump's move to withdraw from the 2015 nuclear deal with Iran. ( AP: Andrew Harnik )

He said Iran must "stop enrichment" of uranium, which was allowed within strict limitations under the 2015 deal. Iran must also allow nuclear "unqualified access to all sites throughout the country," Mr Pompeo said, alluding to military sites that were off-limits under the 2015 deal except under specific circumstances.

To that end, he also said Iran must declare all previous efforts to build a nuclear weapon, reopening an issue that the UN's International Atomic Energy Agency has already deemed a closed matter.

Mr Pompeo also demanded that Iran cease from a range of activities throughout the Middle East that have long drawn the ire of the US and its allies. He said Iran must end support for Shiite Houthi rebels in Yemen, "withdraw all forces" from Syria, halt support for its ally Hezbollah and stop threatening Israel.

Iran must also "release all US citizens" missing in Iran or being held on "spurious charges," he said.

At the same time, Mr Pompeo offered Iran a series of dramatic potential US concessions if it agrees to make "major changes."

Under a new agreement, the US would be willing to lift all sanctions, restore full diplomatic and commercial ties with Iran, and even support the modernization of its economy, Mr Pompeo said.

"It is America's hope that our labours toward peace and security will bear fruit for the long-suffering people of Iran," he said.

Sorry, this video has expired Donald Trump announces US withdrawal from the Iran nuclear deal, imposes sanctions on regime (Photo: AP)

Mr Pompeo's speech came after Mr Trump earlier this month infuriated US allies in Europe by withdrawing from the 2015 deal brokered by President Barack Obama, Iran and world powers. Europeans allies had pleaded with Mr Trump not to scuttle that deal and are now scrambling to keep the deal alive even without the US.

Mr Pompeo called that 2015 agreement a "loser deal".

But the Trump administration has held out hope that those same allies will put aside that frustration and work with the US to ramp pressure back up on Iran through sanctions in a bid to bring Tehran back to the negotiating table for a stronger deal.

Pompeo said he understood that Trump's decision "will pose financial and economic difficulties for a number of our friends." But he warned them that the US planned to follow through with threats to punish European companies that continue doing business with Iran that is allowed under the deal but will violate reimposed US sanctions.

"I know our allies in Europe may try to keep the old nuclear deal going with Tehran. That is their decision to make," Pompeo said. "They know where we stand."

AP/ABC