The US and Israel widened their attacks against Iran's civilian infrastructure on Thursday after President Donald Trump threatened to unleash widespread destruction across the country.
Warplanes destroyed one of the country's oldest medical research institutes in Tehran while a key commuter bridge west of the capital was damaged.
Meanwhile, waves of Israeli attacks have shut down Iran's two largest steel plants, threatening to cripple one of the country's most important industries.
The destruction of civilian sites came hours after the US president threatened to send the country "back to the Stone Ages" if it does not submit to his demands.
It also came on the same day that more than 100 international legal experts expressed "profound concern" at mounting evidence of US war crimes during the punishing 33-day bombing campaign.
Images showed widespread destruction at the prestigious Pasteur Institute of Iran, which has led the country's public health research for more than a century.
Established after the First World War with France's Institut Pasteur, the institute pioneered the development of indigenous vaccines for diseases such as smallpox and Covid-19.
A spokesperson for Iran's health ministry condemned the strike and called on the World Health Organisation and other global health bodies to intervene.
"The aggression against Pasteur Institute of Iran - a century-old pillar of global health and member of International Pasteur Network - is a direct assault on international health security," said Hossein Kermanpour.
Iran's foreign ministry spokesperson called the attack "heartbreaking, cruel, despicable and utterly outrageous".
"This is not merely another war crime committed as part of an illegal war; it is a barbaric assault on basic human core values," Esmaeil Baqaei wrote on social media.
The Pentagon and Israel's Ministry of Defence did not immediately respond to requests for comment. Bridge destroyed In a separate attack, a key highway out of the capital was taken out of action after a strike destroyed a section of the B1 bridge near the city of Karaj.
Videos shared online showed plumes of smoke and a section of the bridge collapsing.
The bridge - the highest in the Middle East - was close to completion and was expected to serve as a key transit route out of Tehran.
Several people were injured in the attack, Iranian media reported.
The attacks are indicative of an increasingly indiscriminate campaign being waged by the US and Israel on Iran's civilian infrastructure.
Oil and gas facilities, steel plants and universities have all come under attack in recent days. Meanwhile, Trump has repeatedly threatened to wipe out the country's electricity grid.
Iran has responded by targeting similar sites across the Gulf, including energy facilities, aluminium plants and buildings hosting US companies.
The Israeli and US air forces have bombed thousands of military and government targets across the country since starting the war on 28 February.
The destruction has failed to curb Iran's military, which has continued to launch missile salvoes and drone attacks across the region.