"Once again, the wicked hands of the global arrogance, with the usurper Zionist regime as the mercenary, were stained with the blood of a son of this nation," Rouhani said in a statement on his official website, referring to the killing of Mohsen Fakhrizadeh.

Iran generally uses the term "global arrogance" to refer to the United States.

Fakhrizadeh was "seriously wounded" when assailants targeted his car before being engaged in a gunfight with his bodyguards in an attack outside Tehran on Friday, Iran's defence ministry said.

It added that Fakhrizadeh, who headed the ministry's reasearch and innovation organisation, was later "martyred" after medics failed to revive him.

Rouhani vowed that his death "does not disrupt" Iran's scientific progress and said the killing was due to the "weakness and inability" of Tehran's enemies to impede its growth.

He offered condolences to "the scientific community and the revolutionary people of Iran."

Iran's foreign minister Mohammad Javad Zarif said on Friday that there were "serious indications of an Israeli role" in the assassination.

The United States slapped sanctions on Fakhrizadeh in 2008 for "activities and transactions that contributed to the development of Iran's nuclear programme", and Israeli Prime Minister Benjamin Netanyahu once described him as the father of Iran's nuclear weapons programme.

Fakhrizadeh was targeted while travelling near Absard city in Tehran province's eastern Damavand county.

The New York Times said an American official and two other intelligence officials confirmed Israel was behind the attack, without giving further details.

The assassination comes less than two months before US President-elect Joe Biden is to take office.

Biden has promised a return to diplomacy with Iran after four hawkish years under Donald Trump, who withdrew from the Iran nuclear deal in 2018 and began reimposing crippling sanctions.

amh/kam/dwo

THE NEW YORK TIMES COMPANY