TEHRAN, Iran — Iranian authorities on Wednesday executed a man convicted of spying for Israel by passing on information about a nuclear scientist killed during the 12-day war with Israel in June, the judiciary said.

“Roozbeh Vadi… was executed following judicial proceedings and confirmation of his sentence by the Supreme Court,” the judiciary’s Mizan Online website said, adding that the man had leaked information about a “nuclear scientist who was assassinated during the Zionist regime’s recent aggression.”

The execution was carried out by hanging, it added.

It was not immediately clear when he was arrested or sentenced.

Mizan reported that Vadi worked at one of Iran’s “key and sensitive organizations” and that his access enabled him to pass on “classified information” after being recruited online by Israel’s Mossad spy agency.

In mid-June, Israel launched an unprecedented bombing campaign against Iran, triggering a war during which Iran responded with missile and drone strikes.

The Israeli offensive killed senior military commanders, nuclear scientists and hundreds of others, striking both military sites and residential areas.

According to local media, at least a dozen nuclear scientists were killed.

Iran has since the war vowed swift trials for people arrested on suspicion of collaborating with Israel.

Authorities have announced multiple arrests of people suspected of spying for Israel and the executions of several convicted of working with Mossad.

Separately on Wednesday, authorities executed a man convicted of being a member of the extremist Islamic State group, who was allegedly planning “terrorist operations inside Iran,” according to Mizan.

Iran is the world’s second-most prolific executioner after China, according to human rights groups, including Amnesty International.

Israel said its sweeping assault on the country’s top military leaders, nuclear scientists, uranium enrichment sites, and ballistic missile program was necessary to prevent the Islamic Republic from realizing its avowed plan to destroy the Jewish state.

After 12 days of fighting, at the end of which the US also hit three Iranian nuclear sites, Washington brokered a ceasefire.

Israeli authorities themselves have boasted about the deep penetration into Iran that their intelligence agencies achieved to plan for its attack, including footage purporting to show agents launching drones from within Iran.

Iran responded to the attacks by firing hundreds of missiles at Israeli cities that killed 29 people and injured over 3,000. It has faced continuing internal instability since the war ended and has launched a sweeping internal crackdown aimed at rooting out Israeli spies, dissidents, and opposition figures.