Iran has arrested 20 people it alleges are operatives of Israel’s Mossad spy agency in recent months, Tehran’s judiciary said on Saturday, warning that they will face no leniency and will be made an example of.

On Wednesday, Iran executed a nuclear scientist named Rouzbeh Vadi, who was convicted of spying for Israel and passing along information on another nuclear scientist killed in Israel’s air strikes on Iran in June, state media reported.

Judiciary spokesperson Asghar Jahangiri told reporters in Tehran on Saturday that charges against some of the 20 suspects had been dropped and they were released. He did not give a number.

“The judiciary will show no leniency toward spies and agents of the Zionist regime, and with firm rulings, will make an example of them all,” Jahangiri was quoted as saying by Iranian media.

He said full details would be made public once investigations were complete.

Executions of Iranians convicted of spying for Israel have significantly increased this year, with at least eight death sentences carried out in recent months.

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.

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 obtaining a nuclear weapon and realizing its avowed plan to destroy the Jewish state.

Since the war, Iranian authorities have announced multiple arrests of people accused of spying for Israel and the executions of several convicted of working with Mossad. Israel does not comment on such claims.

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 is the world’s second-most prolific executioner after China, according to human rights groups. It rarely publicly produces evidence of the crimes those executed have been convicted of.

Times of Israel staff contributed to this report.