An Iranian Senator has offered a US$3 million ($4.4 million) reward to anyone who kills US President Donald Trump, the state-run news agency ISNA has reported.

Key points: This is not the first time a bounty has been placed on US President Donald Trump

This is not the first time a bounty has been placed on US President Donald Trump The US has called Iran's $3 million reward to kill Mr Trump "ridiculous"

The US has called Iran's $3 million reward to kill Mr Trump "ridiculous" Iran's Senator Ahmad Hamzeh also said they would be safer if they had nuclear weapons.

Tensions have steadily escalated since Mr Trump pulled Washington out of Tehran's nuclear agreement with world powers in 2018 and reimposed US sanctions. The standoff erupted into tit-for-tat military strikes this month.

"On behalf of the people of Kerman province, we will pay a $3 million reward in cash to whoever kills Trump," Senator Ahmad Hamzeh told the 290-seat parliament, ISNA reported.

He did not say if the idea of a reward had any official backing from Iran's clerical rulers.

The city of Kerman, in the province south of the capital, is the hometown of Qassem Soleimani, a prominent Iranian commander whose killing in a drone strike ordered by Mr Trump on January 3 in Baghdad prompted Iran to fire missiles at US targets in Iraq.

US disarmament ambassador Robert Wood told reporters in Geneva the bounty offer pointed to the "terrorist underpinnings" of the Iranian government.

"It's just ridiculous but it gives you a sense of the terrorist underpinnings of that regime and that regime needs to change its behaviour," Mr Wood said.

It is not the first time a public bounty has been placed on Mr Trump from disgruntled Iranians. Reportedly an identified eulogist speaking at the funeral of General Soleimani asked Iranians to raise $80 million for "anyone who get close to the head of Trump".

Iranian lawmakers attend a session of parliament in Tehran. File picture. ( Reuters: Nazanin Tabatabaee, West Asia News Agency )

US and Iran relationships hit a low

The death of General Soleimani at Baghdad Airport, portrayed as a national hero at home but viewed as a dangerous enemy in the West, led to huge mourning ceremonies in Iran.

Some analysts have called it a watershed moment in the Middle East conflict.

Neither the President nor his advisers have provided public information to back up their statements that General Soleimani presented an "imminent" threat to Americans in the region.

Last week, Mr Trump gave a minute-to-minute account of the US drone strike that killed Iranian military commander Qassem Soleimani to a Republican fundraising dinner.

However, Mr Trump did not repeat that General Soleimani was an imminent threat, but said General Soleimani was "saying bad things about our country" before the strike, which led to his decision to authorise his killing.

It prompted Iran to retaliate with missile strikes against US forces in Iraq days later and almost triggered a broad war between the two countries.

While on high alert for further US action, Iran then accidently shot down a Ukrainian passenger plane, killing all 176 on board.

The victims included 57 Canadian citizens as well as 11 Ukrainians, 17 people from Sweden, four Afghans and four British citizens.

Nuclear deal stand-off

The US and its Western allies have long accused Iran of seeking nuclear weapons.

Tehran insists it has never sought nuclear arms and never will, saying its nuclear work is for research and to master the process to generate electricity.

The 2015 nuclear agreement as a whole was designed to increase the time Iran would need to obtain enough fissile material for a nuclear bomb — the main obstacle to producing a nuclear weapon — from around two or three months.

Under the deal, Iran received sanctions relief in return for curbing its nuclear activities.

In response to Washington's withdrawal from the pact and pressure from US sanctions, Iran has gradually rolled back its commitments to the nuclear deal.

This month, Iran announced it was scrapping all limits on its uranium enrichment work, potentially shortening the so-called "breakout time" needed to build a nuclear weapon.

Reports issued by the UN nuclear watchdog have suggested Tehran is still far from sprinting ahead with its work.

After its latest move to step away from compliance with the deal, European states Britain, France and Germany triggered a dispute mechanism in the pact, starting a diplomatic process that could lead to reimposing UN sanctions.

Iran said on Monday that Tehran would pull out from the Non-Proliferation Treaty (NPT) if international sanctions were reimposed on the country. The 1968 NPT has been the foundation of global nuclear arms control since the Cold War.

Senator Hamzeh said it was his country's "natural right" to have a nuclear program.

"If we had nuclear weapons today, we would be protected from threats," Mr Hamzeh said.

"We should put the production of long-range missiles capable of carrying unconventional warheads on our agenda. This is our natural right."