The United Nations' sweeping economic and military sanctions look set to be reimposed on Iran a decade after they were lifted in a landmark international deal over its nuclear programme.

It comes after the UK, France and Germany wrote to the UN Security Council last month, accusing Iran of failing to fulfil its commitments. That triggered a mechanism giving Iran 30 days to find a diplomatic solution to avert renewed sanctions.

Iran's President Masoud Pezeshkian condemned the re-imposition of international sanctions as unfair, unjust, and illegal. A last-minute resolution, led by China and Russia, to delay the move by six months only received four votes in the 15-member council.

The sanctions are set to come into force at 00:00 GMT on Sunday. Iran stepped up banned nuclear activity after the US quit the deal in 2016. Donald Trump pulled the US out in his first term, criticizing the Joint Comprehensive Plan of Action (JCPOA) negotiated by Obama as flawed.

Iran barred IAEA inspectors from accessing its nuclear facilities after Israel and the US bombed several of its nuclear sites in June following deadlocked negotiations to reach a new nuclear deal.

President Pezeshkian stated at the UN this week that Iran would never seek to build a nuclear bomb and accused foreign powers of seeking a pretext to escalate tensions.

Unless a solution is found, UN sanctions would come into force first, followed by EU sanctions next week. European foreign ministers had urged Iran to resume negotiations with the US and cooperate with the IAEA.

Challenges remain, as Iranian Foreign Minister Abbas Aragchi emphasized that the US has betrayed diplomacy. The IAEA confirmed that inspections of Iranian nuclear sites had resumed this week after a hiatus caused by attacks.

Russia struck a $25 billion deal with Iran to construct four nuclear reactors, reflecting ongoing tensions and complexities in the region.