The announcement came days after Washington imposed new sanctions on Iran, and amid crucial talks in Vienna to salvage the 2015 Iran nuclear deal.

Retired US General Joseph Votel, who headed US Central Command which covers the Middle East, is among the 24 sanctioned Americans. Other US former treasury and military officials, ambassadors and company managers are also on the list.

They are targeted for "their involvement in terrorist acts, glorification and supporting terrorism and gross violations of human rights," a statement by Iran's foreign ministry said.

The nuclear deal between Tehran and world powers, known as the Joint Comprehensive Plan of Action (JCPOA), gave Iran sanctions relief in exchange for curbs on its nuclear programme.

It aimed to prevent Tehran from developing a nuclear weapon, something it has always denied wanting to do.

The US unilaterally withdrew from the accord in 2018 and reimposed biting economic sanctions, prompting Iran to begin rolling back on its own commitments the following year.

US sanctions "including by deprivation of access to medicine and medical equipment and services, especially, in the situation caused by the Covid-19 pandemic... has endangered lives of millions of Iranians," the foreign ministry statement said.

"Such unlawful measures constitute flagrant violations of the fundamental principles of international law and fundamental human rights and are a clear example of crime against humanity."

The Vienna negotiations that started about a year ago involve Iran as well as France, Germany, Britain, Russia and China directly, and the United States indirectly.

Talks had progressed most of the way toward reviving the deal. They were halted on March 11 after Russia demanded guarantees that Western sanctions imposed following its invasion of Ukraine would not damage its trade with Iran.

Days later, Moscow said it had received the necessary guarantees, but the impasse continued as Tehran and Washington traded accusations over causes of the delay.

In late March, the US Treasury announced sanctions targeting several entities it accused of involvement in procuring supplies for Iran's ballistic missile programme.

A day later, Iran's foreign ministry spokesman said Washington's latest sanctions showed its "ill will" towards the country.