President Joe Biden has cautioned Rishi Sunak against censuring Iran over its nuclear programme amid high tensions in the Middle East.

The International Atomic Energy Agency's 35-nation Board of Governors passed a resolution against Iran 18 months ago, demanding it to cooperate with a years-long investigation into uranium particles found at three undeclared sites.

European powers, including Britain and France, are believed to be preparing a censuring resolution.

However, the Biden administration has asked the countries to abstain from the resolution and said it will do the same.

Concern about Iran’s atomic ambitions have grown since 2019 when then president Donald Trump pulled the US out of a deal offering sanctions relief in exchange for curbs to its nuclear programme.

The country has been enriching uranium to 60 per cent purity, close to the roughly 90 per cent that is weapons-grade, for three years. Iran has consistently denied seeking a nuclear weapon and says all its activities are peaceful.

Western powers say there is no credible civilian energy purpose in enriching to that level, and the IAEA says no other country has done so without going on to make a nuclear weapon.

One senior European diplomat said: "There is no slowing down of its programme and there is no real goodwill by Iran to cooperate with the IAEA...all our indicators are flashing red.”

Officials have been citing the US presidential election as a reason for the Biden administration's reluctance.

But the main argument US officials make is to avoid giving Iran a pretext to respond by escalating its nuclear activities, as it has done in the past.

There have been complications in talks following the death of President Ebrahim Raisi's death in a helicopter crash earlier this month.

During talks aimed at improving Iran's cooperation with the IAEA, Tehran told reporters it would not engage with it until Raisi's successor is elected on June 28, two diplomats said.

Israel and Iran carried out direct strikes on each other for the first time last month, and Israel has repeatedly threatened to attack Iran's nuclear facilities.

Meanwhile, eyewitnesses in Gaza said Israeli tanks reached the centre of Rafah earlier today in a move that has sparked global condemnation.

Residents said Israeli forces pounded the city with airstrikes and tank fire, depsite international outcry over an attack on Sunday that sparked a blaze in a tent camp, killing at least 45 Palestinians, more than half of them children, women and the elderly.

Since that strike, at least 26 more people have been killed by Israeli fire in Rafah, officials in the enclave run by Hamas militants said.