"The execution sentence was carried out for Jalal Haji Zavar, a contractor for the defence ministry's aerospace organisation who spied for the CIA and the American government," ISNA reported, quoting the Iranian military.

ISNA said he was convicted by Iran's military court and that he was executed, at an unspecified time, at the Rajayi Shahr prison in the city of Karaj, west of Tehran.

The agency did not say when Zavar was arrested, noting however that his contract with the defence ministry had been terminated during the Iranian year 1389 (March 2010-2011).

He was identified as a spy by the defence ministry's intelligence unit, ISNA said.

During the investigation the suspect "explicitly confessed to spying for the CIA" in return for money, ISNA said, adding that "documents and espionage devices were found at his house".

Zavar's ex-wife was convicted of "involvement in espionage" and is serving a 15-year jail sentence, the agency said.

The report comes days after Iran said it had dismantled a "new" US spy network in the country linked to the CIA, amid escalating tensions between Tehran and Washington.

In what it termed a "wide-reaching blow" to US intelligence, state news agency IRNA said on Tuesday that Tehran had carried out the operation in cooperation with "foreign allies", without naming any state.

Tensions between Washington and Tehran flared up after Iran, on Tuesday, said it shot down a US "spy" drone which violated its airspace -- a claim the US denies -- near the strategic Strait of Hormuz.

In response, the US was ready to carry out a military strike against Iran.

President Donald Trump said Friday the United States was "cocked & loaded" to strike Iran but pulled back at the last minute as it would not have been a "proportionate" response to Tehran's shooting down of the unmanned drone.

The downing of the drone came after tensions spiked between the two countries following a series of attacks on oil tankers the US has blamed on Iran.