US intelligence agencies have reported a sharp rise in Iran’s attempts to target American diplomats and government officials in the Middle East and other parts of the world, according to a report by Axios.

A memo dated October 23, obtained by the US news outlet, states that some suspected Iranian plots involving potential loss of life have reached “advanced stages”. The threat has raised concerns among US security officials and prompted the State Department to reduce staffing at several American diplomatic missions in the Middle East.

Washington is also monitoring the possibility of Iran-backed Houthi rebels in Yemen expanding their attacks beyond Saudi Arabia to other countries in the region. Potential fresh US and Israeli strikes against Iran, possibly after the US midterm elections, have added to concerns over a wider conflict.

The unclassified memo to Secretary of State Marco Rubio reveals that Director of National Intelligence Jay Clayton has urged wider circulation of warnings about suspected Iranian assassination operations.

Clayton warned that restrictions on access to intelligence could prevent vulnerable American personnel from receiving crucial security information. Although the memo does not identify potential targets, specific operations or locations outside the Middle East, it confirms that senior State Department officials have received the intelligence.

Clayton proposed removing classified restrictions wherever possible to allow Rubio to share the threat assessments with more American officials.

US President Donald Trump threatened Tehran on Friday, suggesting Washington could launch fresh military action if Iran failed to reach a diplomatic agreement.

Addressing a campaign rally in Florida, Trump defended his national security record and criticised Iran’s leadership.

"We may do another little Epic Fury, or they'll agree," Trump told the cheering crowd, as quoted by Fox News.

"If they're smart, they'll just say, 'Let's get down to business.' But, you know, I doubt they'll do that because perhaps they're not smart," he added.

Last week, the State Department asked family members and nonessential personnel to leave the US Embassy in Riyadh and the consulates in Jeddah and Dhahran.

A US official confirmed on Friday that Washington had ordered several diplomatic missions to reduce staffing in the UAE, Lebanon, Qatar and Jordan.

"We decided that due to the threat of Houthi attacks and Iranian terror plots, we need to reduce our footprint and keep only essential staff," the official told Axios.

CNN had also reported staff reductions at the four embassies.