Tehran, Iran (CNN) Iran has detained 17 Iranian citizens accused of acting as spies for the United States Central Intelligence Agency, according to the country's Ministry of Intelligence.

An Intelligence Ministry document sent to CNN claims Iran had broken up a CIA spying ring and captured 17 suspects, all of whom confessed to acting as spies for the CIA.

"Defendants serving their sentences in prison mentioning tempting promises of CIA officers including emigration to USA, a proper job in America, and money," the Intelligence Ministry document said. It added that the spy mission was to collect classified information "from substantial centers as well as intelligence/technical operations."

The ministry said some of the 17 will be executed.

US Secretary of State Mike Pompeo urged caution in response to the announcement. Speaking on the Fox & Friends morning news show, he said: "The Iranian regime has a long history of lying ... I would take with a significant grain of salt any Iranian assertion about actions they've taken."