Protesters commemorating people killed during a deadly government crackdown in Iran last month have clashed with security forces at a university in Tehran.
Students chanted anti-regime slogans, including "death to [Supreme Leader Ayatollah Ali] Khamenei".
They faced off with members of the Basij, a volunteer internal police force which is a branch of the Islamic Revolutionary Guard Corps, according to anti-government media.
Footage shows violent clashes at the Sharif University of Technology on Saturday, while other clips on social media showed protesters with bloody head injuries.
There were also reported demonstrations at the Amir Kabir University of Technology and the University of Tehran.
The protests followed a brutal crackdown on dissent in January which saw thousands of people killed.
Meanwhile, US President Donald Trump is considering military action against Iran.
Mr Trump warned on Friday that strikes were possible even as Iran's top diplomat said Tehran expected to have a proposed deal ready in the next few days.
It follows talks with the US over Iran's nuclear programme.
America has scaled up its military presence in the Middle East in recent weeks.
The aircraft carrier USS Abraham Lincoln and its strike group will shortly be joined by the USS Gerald Ford, which passed Gibraltar on Saturday en route to the region.
"I guess I can say I am considering that," said Mr Trump when asked by a reporter at the White House on Friday about a limited strike on Iran.
Steve Witkoff, Mr Trump's special envoy to the Middle East, said the president was "curious" as to why Iran had not "capitulated" amid the naval build-up in the region.
"I don't want to use the word 'frustrated', because he understands he has plenty of alternatives, but he's curious as to why they haven't... I don't want to use the word 'capitulated', but why they haven't capitulated," Mr Witkoff told Fox News.
"Why, under this pressure, with the amount of sea power and naval power over there, haven't they come to us and said, 'we profess we don't want a weapon, so here's what we're prepared to do'? And yet it's sort of hard to get them to that place."
What Iran's president has said
Masoud Pezeshkian, Iran's president, sounded a defiant tone during a meeting with Paralympic athletics on Saturday.
"We will not bow our heads in the face of these problems," he said. "We will try to bring honour and pride to our country.
"As long as we are alive, and we can breathe, we will sacrifice our lives for our country.
"By God's grace and strength, we will not lower our heads in the face of these difficulties. Even though the outside world and global powers are unfairly pressing us to submit, we will not bow our heads, just as you [athletes] refused to bow to difficulties."
Read more:
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UK has not agreed to let US strike Iran from British bases
Mr Trump talked up regime change in Iran on 13 February when he revealed that a second aircraft carrier was heading to the Middle East.
"It seems like that would be the best thing that could happen," Mr Trump said. "For 47 years, they've been talking and talking and talking.
"In the meantime, we've lost a lot of lives while they talk. Legs blown off, arms blown off, faces blown off. We've been going on for a long time."
(c) Sky News 2026: Iranian students clash with security forces during protests amid Donald Trump warn
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