An Iranian citizen who provided information to US and Israeli intelligence services about whereabouts of Iran's top commander Qasem Soleimani will be executed soon, Iran's judiciary spokesman said today.

"Mahmoud Mousavi-Majd, one of the spies for CIA and Mossad has been sentenced to death.

"He gave the whereabouts of martyr Soleimani to our enemies," said Gholamhossein Esmaili in a televised news conference.

On 3 January a US drone strike in Iraq killed Soleimani, the head of Iran's elite Quds Force.

Top Iraqi militia commander Abu Mahdi al-Muhandis, an adviser to General Soleimani, was also killed in the attack.

General Soleimani's killing marked a dramatic escalation in the regional "shadow war" between Iran and the US and its allies, principally Israel and Saudi Arabia, raising fears of an increase in tit-for-tat attacks.

Iran's Supreme Leader Ayatollah Ali Khamenei vowed harsh revenge.

In the aftermath of the airstrike, the US embassy in Baghdad urged its citizens to "depart Iraq immediately".