Iran is currently gripped by the largest -- and most significant -- wave of unrest in its recent history.
The protests, sparked by the death of Mahsa Amini on 16 September, have swept across the country, with security forces cracking down hard on demonstrators.
While internet access is heavily restricted in Iran, photos and videos have nevertheless spread on social media that claim to show UK weapons are being used to suppress protestors.
But is this the case?
Several images shared on Twitter purport to show that non-lethal, UK-made weapons, such as stun grenades and flash bangs, have been deployed against demonstrators.
One of these images is a stun grenade canister, which clearly displays the word "England".
Many have seized upon this as evidence UK weapons are helping Iran's security forces stamp out dissent, claiming Britain is somehow implicated in the violence and bloodshed in Iran.
But it is not so simple.
According to Forensic Architecture, a UK-based research group that investigates state violence, the text on the canister photographed above reads "Limited High Post Wiltshire England", which they say means it is likely from a defunct UK arms company, Old Schermuly Limited.
The stun grenade, they told Euronews, is "an old model, so [it was] probably sold years back".
In 1978, when the country was still ruled by the pro-Western Shah, himself installed by the US and UK in a coup, Schermuly exported large quantities of non-lethal weaponry to Iran.
That year it was reported that Schermuly exported to Iran 13,000 anti-riot guns, 26,000 CS gas cartridges and 20,000 mini smoke grenades, 20,000 anti-riot helmets, 20,000 gas masks and 20,000 riot shields, while 2,000 anti-riot guns were also 250,000 rubber bullets.
At the time, the Shah was wrestling with mass civilian unrest in Iran, which culminated in the 1979 Islamic Revolution.
Much of this equipment will have been used or fallen into disrepair, though there is the possibility some of it remains in use, as the above image suggests.
Yet UK-made weapons are not only reportedly being used on the streets.
Dr Kylie Moore-Gilbert, a British-Australian academic, spent two years in Iran's notorious Evin Prison from 2018 to 2020 on charges of espionage, though no evidence of her alleged crimes was ever offered by the Iranian government.
During her time in jail, she told Euronews that handcuffs with the words "Made in England" stamped on them were put on her and other prisoners inside Evin.
"The model of the handcuffs looked old" and "had a very old fashioned looking key", she said, suggesting that the "cuffs very well could be from before the revolution".
"They were in good condition, however - polished silver, in good working order," she added.
Other former detainees in Evin have made similar comments about the use of British handcuffs inside the facility.
Evin Prison -- where a large, deadly fire broke out last weekend -- is traditionally used by the Iranian government to house political prisoners, earning it the nickname "Evin University" due to the number of students and intellectuals imprisoned there.
Hundreds of those taking part in the current protests have been detained in Evin.
Not all images which supposedly document UK weapons being shared online are accurate, however.
The above image of a flashbang cartridge has been shared multiple times on social media, with many claiming it originates from the UK.
Publishing the picture, the Iranian news website Peykeiran wrote: "The people of Iran want the British Foreign Minister to explain how this tear gas they are firing in Tehran is made in England in 2020."
"You supply the equipment of the child-killing regime and at the same time you claim to support the fighting people of Iran," it added.
Yet there is no concrete evidence that this shell originated from the UK or was produced by a British company.
While the cartridge has English written on it, "companies all around the world write their labels in English," says Forensic Architecture. "We cannot see anything that indicates that it was produced in the UK."
Manufacturers of flash bangs and other non-lethal weapons often use generic cartridges, which are deployed by authorities around the world.
Iran itself has had the ability to manufacture many non-lethal weapons for "many, many years", said the Omega Research Foundation, another independent research organisation based in the UK.
What this suggests is that most of the weaponry used against protestors is Iranian-made.
Under tight international sanctions, which prevent it from importing many goods, Iran's defence industry is well developed, capable of producing its own tanks, aircraft and missiles.
Between 2012 to 2021, the UK did not sell any military equipment to Iran due to sanctions, according to a report by Armed Action on Armed Violence shared with Euronews.
It has respected the various arms embargoes on Iran, only exporting dual-use items to the country, such as aircraft parts.
The UK has repeatedly condemned Iran for alleged human rights abuses against its population, sanctioning the country in October over Tehran's deadly response to protestors.
At least 233 protesters have been killed since demonstrations broke out, according to US rights monitor HRANA. The group said 32 of the dead are children and teenagers.