PARIS, France (AFP) — The United States (US) authorised the departure of non-emergency embassy staff from Israel on Friday, as it threatened strikes on Iran and pressed its biggest military build-up in the Middle East in decades.

The move came a day after a round of Oman-mediated talks between Iran and the US, seen as a last-ditch bid to avert war, though initial optimism was tempered by Tehran warning Washington must drop “excessive demands” to reach a deal.

The talks follow repeated threats from President Donald Trump to strike Iran while the US military builds up its forces in the region.

As the world’s largest aircraft carrier, the USS Gerald R. Ford, was due to arrive off the coast of key US ally Israel, the US embassy in the country announced it was allowing non-emergency government personnel and family members to leave “due to safety risks”.

“Persons may wish to consider leaving Israel while commercial flights are available,” the embassy said on its website.

The New York Times reported that US Ambassador to Israel Mike Huckabee sent an email to embassy staff on Friday morning saying that those wishing to leave “should do so TODAY”.

“Focus on getting a seat to anyplace from which you can then continue travel to DC, but the first priority will be getting expeditiously out of country,” he was quoted as writing.

Growing concerns over conflict spurred China on Friday to join other countries in warning its citizens to leave Iran “as soon as possible”.

Trump on February 19 gave Iran 15 days to reach a deal. While Iran has insisted the discussions focus solely on nuclear issues, the United States wants Tehran’s missile programme and its support for militant groups curtailed.

The Wall Street Journal reported on Thursday that Trump’s negotiating team would demand that Iran dismantle its three main nuclear sites and hand over all its remaining enriched uranium to the United States.

Without specifying what demands he was referring to, Iran’s Foreign Minister Abbas Araghchi said on Friday that “success in this path requires seriousness and realism from the other side and avoidance of any miscalculation and excessive demands”.