Ukraine's emergency alert app issued a nationwide air raid warning, as well as alerts for a radiological threat, a chemical attack and street fighting in Kyiv on Sunday evening — all of which turned out to be false. This was reported by Qazaqyia.kz citing BBC News.

A few hours later, Russia said its equivalent app had also issued false alerts, with both countries claiming their systems had been hacked.

It is still unclear who is to blame for the cyber-attacks and whether the two incidents are connected — the BBC's cyber correspondent Joe Tidy explains what we know so far.

The incident occurred on Sunday evening in Ukraine: the emergency alert app sent a nationwide air raid warning, as well as messages about a radiological threat, a chemical attack and street fighting in Kyiv. Later, all these alerts were confirmed to be false.

A few hours later, Russian authorities reported that their equivalent app had also issued false alerts. Both countries claim their systems were hacked.

Currently, it is unknown who is responsible for the cyber-attacks and whether the two incidents are connected. The BBC's cyber correspondent Joe Tidy presents the known facts on the matter.

This incident highlights the vulnerability of emergency alert systems in Ukraine and Russia. Both countries have previously reported cyber-attacks. However, it has not yet been established who is behind them.