Reported by BBC World
Ukrainians are used to reacting to the warnings of Russian attacks sent via the air alert app
Ukraine's air raid alert app was apparently hacked on Sunday and for a short time said the capital Kyiv was subject to a radiation threat, the Ukrainian Air Force has said.
The alert on Telegram read: "The Air Alarm application has probably been subjected to hostile interference. There is no radiation threat! Stay calm and follow our updates on our channel."
More from the original report
The Ukrainian Central Intelligence Agency said there had been a failure in the app, and urged people to use other sources of information to clarify the situation on the threat of air strikes.
The alerts, in Ukrainian, started at approximately 22:47 (20:47 GMT), with the first reading: "Radiation threat. Radiation threat declared in Kyiv."
The next message, written in Russian, came at 22:48, which read: "Hi! There will be a nuclear alert across Ukraine. Don't worry, it's Oreshnik flying".
A third alert, at 22:49, again in Ukrainian, said "Chemical threat. There is a threat of a chemical attack on Kyiv. Don't go outside."
At 22:49, a fourth alert stated there was a "Street fighting threat. Street fighting is taking place in Kyiv. Don't go outside."
At 23:53 a series of all clear messages were then delivered to users' phones, which were connected to each of the previous Kyiv alerts, individually declaring each threat clear.
In a separate post on Telegram, the Ukrainian Central Intelligence Agency said that due to the Air Alert application, the Radiation Hazard signal was played on loudspeaker devices in the Lviv region, and added there was no threat of radiation hazard.
If the alert app is not working, Ukraine's Centre for Countering Disinformation advises the public to turn on notifications on their smartphones, pay attention to sirens, and to only read official sources
Several governors of other regions also posted on Telegram that the app had apparently been hacked and there was no local threat.
"Everything is calm in the region for now," said Svitlana Onyshchuk, the governor of the Ivano-Frankivsk Oblast. The app had reported a red-level…