'Like a sound from hell': Serbia and sonic weapons
Pressure is building on the Serbian government after reports that it used an illegal sonic weapon on protesters in Belgrade.
Tens of thousands of people were holding a peaceful anti-corruption rally when "we heard something we could not see", said protester Ivana Ilic Sunderic, "ike a sound rolling toward us". It was "very unusual and very frightening, like a sound from hell", she told Sky News.
Serbian authorities denied the use of an acoustic weapon. But as video footage emerges of the incident, there is "mounting speculation" about the dispersal tactics used by security forces, and more than half a million people have signed a petition demanding an independent investigation.
What happened at the protest?
The rally, on 15 March, was one in a string of "near-daily protests" triggered by the collapse of a train-station roof in the northern city of Novi Sad. The disaster, which killed 15 people, "became a flashpoint" for Serbs unhappy with their country's "increasingly authoritarian rule", said The Guardian.
Video footage of the rally published by The Associated Press appears to show "thousands of protesters, holding up their lit mobile phones in silence, when they suddenly start running away in panic". A "swooshing sound" can then be heard.
Campaigners say this was the moment when protesters "were targeted" with a "sound cannon". Sonic weapons, illegal in Serbia, send out sound waves, which can cause ear pain, disorientation, eardrum rupture or even permanent hearing damage. After the rally, protesters posted on social media that they were suffering from "lingering headaches, nausea and ringing in the ears", said The Guardian.
President Aleksandar Vucic said it was "wicked lie" that a sonic weapon had been used on the crowd, but a photo taken at the protest appears to show "a police vehicle with a large piece of equipment fixed to the bonnet".
What do the experts say?
When presented with the photo, officials admitted possessing a sonic weapon but "insisted it was not used" at the rally, said The Independent. Interior Minister Ivica Dacic said the vehicle housed nothing more than "loudspeakers" that simply "serve to emit warnings to the crowds in case of major trouble".
The photo shows "what appears to be a LRAD 450XL" sonic weapon, said The Independent. Genasys, the US manufacturer, said neither the photo nor the video suggest that an LRAD was used.
But some experts disagree. Thomas Withington, an electronic-warfare expert from the Royal United Services Institute reviewed the "extraordinary film" of the incident and told The Independent he'd never seen anything like the "almost kind of biblical passing of a huge number of people in a panicked rush".
And Predrag Petrovic, from the Belgrade Center for Security Policy, said there was a "huge probability" that "some version of a sonic cannon" was used. "I have a lot of experience in participating and monitoring street protests, and I have never seen a stampede happen in a second, and along an almost straight line", he told the paper.
What could happen next?
The petition, organised by the Serbian opposition Move-Change movement, calls on the United Nations, the Council of Europe and the Organisation for Security and Cooperation in Europe to open an independent investigation.
Several Serbian rights organisations have also "taken the issue to the European Court of Human Rights", said AP. They claim to have "collected more than 4,000 testimonies" from people had "various physical and psychological problems" after the incident. Serbia has until the end of this month to respond.
The Serbian government, in the meantime, says it has asked the American FBI and the Russian FSB to investigate.