Iranian intelligence ministry officials on Monday said they had arrested 17 local spies associated with the United States’ Central Intelligence Agency and sentenced some of them to death, AFP reported.

An unidentified director general of the intelligence ministry said it had dismantled the spy network on June 18. “Sentences for these spies have been issued, some of whom are to be put to death as ‘corruptors on earth’,” BBC reported quoting the Iranian Students News Agency.

The spies were reportedly part of sensitive bodies such as economic, nuclear, military and cyber organs, and in private sectors who allegedly worked for the investigating agency as contractors, the director general added. The spies were operating by themselves and none of them were in touch with the others, the report said.

Confirming the development, Ali Shamkhani, secretary of Iran’s Supreme National Security Council, said the cooperation between Iran and other countries had resulted in “the disclosure and dismantling of a network of CIA officers, as well as the detention and punishment of several spies”, reported Mehr news agency.

However, United States President Donald Trump dismissed Iran’s claims. He called the claims “totally false”. “The Report of Iran capturing CIA spies is totally false,” he tweeted. “Zero truth. Just more lies and propaganda (like their shot down drone) put out by a Religious Regime that is Badly Failing and has no idea what to do. Their Economy is dead, and will get much worse. Iran is a total mess!”

Tehran’s announcement comes amid escalating tension between Iran and other countries. Last week, Iran captured a British tanker in the Strait of Hormuz after the United Kingdom’s Royal Marines seized an Iranian tanker near Gibraltar on July 4. As many as 18 Indians, including the captain, are on board the British tanker that Iran’s Islamic Revolutionary Guard Corps had seized, claiming it was in violation of international maritime regulations.

Tensions between Iran and the United States have also steadily increased since last month, when Tehran shot down an American spy drone over the Strait of Hormuz. While Iran claimed the drone had violated its airspace, the US maintained it was shot down over international waters.