Iran's intelligence ministry on Friday published a report in which it accused foreign "enemies" and dissidents of fomenting fears over suspected poisonings of schoolgirls. It said the ministry's investigation found no actual poisoning.

"The enemies' role in fuelling this crisis is certain and undeniable. Individuals, groups and Western media (especially in Persian language)... have focused on this in the past few months, as well as foreign politicians and international bodies," said a ministry report carried by state media on Friday.

"In field findings and laboratory investigations ... no toxic substance able to cause poisoning was observed ... and there have been no deaths or long-term physical conditions," the report said.

The report warned of "prosecution of individuals, groups, media who accused the government ... and aligned themselves with enemies."

The intelligence service also accused foreign players like the United States and Israel of playing a role in the cases in order to trigger further anti-government protests in the country.

Public outrage and mass protests

The suspected poisonings began in November in the holy Shi'ite Muslim city of Qom and spread to 28 of Iran's 31 provinces, according to activist HRANA news agency.

Throughout the country, schoolgirls have been treated in hospitals, with doctors speaking of gas poisoning.

The incidents prompted some parents to take children out of school and protest.

The authorities' hesitant handling of the cases drew sharp criticism in Iran. It took months for the state leadership to comment on the incidents.

The Islamic nation's Supreme Leader Ayatollah Ali Khamenei recently said the perpetrators should be severely punished.

The string of suspected poisonings came more than five months into nationwide protests following the death in police custody of a young Iranian Kurdish woman, 22-year-old Jina Mahsa Amini who had been arrested for an alleged breach of strict dress rules for women.

The demonstrations posed one of the biggest challenges to Iran's clerical rulers since the 1979 Islamic revolution.

Human rights organization Amnesty International recently called for more clarification on the suspected poisonings. In a statement earlier this month, Amnesty spoke of "ongoing gas attacks" that appear to be "a coordinated campaign to punish schoolgirls for their peaceful participation in nationwide protests."