The World Health Organization warned Friday about "multiple attacks on health" in Iran in recent days following an airstrike on the Pasteur Institute in Tehran.

"Multiple attacks on health have been reported in the Iranian capital, Tehran, in recent days amid the escalating conflict in the Middle East," WHO chief Tedros Adhanom Ghebreyesus wrote on X.

He said the Pasteur Institute "sustained significant damage and was rendered unable to continue delivering health services" -- one of 20 facilities the WHO has confirmed as being targeted. 

Iranian health ministry spokesman Hossein Kermanpour posted pictures on X on Thursday showing a heavily damaged building, with parts of the facility reduced to rubble. 

Iran's ISNA news agency reported that the "services of the Pasteur Institute of Iran have not been interrupted by these attacks", adding that vaccine and serum production would continue.

"Fortunately, none of the employees of the Pasteur Institute in Iran were harmed in the recent attacks by the United States and the Zionist regime," it wrote on the Telegram messaging app.

The Pasteur Institute of Iran, which has no formal links with the original Pasteur Institute in Paris, is one of the oldest research and public health facilities in Iran, having been founded in 1920.

Tedros said that the centre "plays an important role in protecting and promoting population health, including in emergencies".

- Targets -

Israel and the United States appear to be widening their targets beyond military, security and administrative infrastructure which were the focus of attacks during the first weeks of the war.

Health, educational and most recently transport infrastructure have been hit in the past days. 

Iran's Mehr news agency, citing the Iranian Red Crescent, reported a strike on a laser and plasma research facility of the Shahid Beheshti University in Tehran on Friday.

The university said in a statement that a "significant part of this center was destroyed" while calling it an attack on "reason, research, and freedom of thought".

Israel has targeted the Imam Hossein University and the Malek-Ashtar University, claiming both were being used for military research. 

One of Iran's largest pharmaceutical companies, Tofigh Daru, which produces anaesthetics and cancer drugs, was attacked on Tuesday. 

Tedros said the Delaram Sina Psychiatric Hospital had also sustained significant damage last Sunday.

Healthcare facilities are protected locations under the Geneva Conventions agreed as the rules of war by world powers after World War II.  

According to the latest figures from the Iranian Red Crescent, 307 health, medical and emergency care facilities have been damaged in the war.

US President Donald Trump has threatened to bomb Iran "back to the Stone Ages", despite international law prohibiting the targeting of civilian infrastructure. 

Israel repeatedly attacked hospitals in Gaza during its two-year bombardment of the territory from October 2023, claiming they were being used by operatives from the Hamas militant group. 

The US and Israel attacked Iran on February 28, claiming the country was rushing towards developing a nuclear weapon, which Tehran has denied.