The BBC's Newsday programme has just spoken to Herbert Lin, a senior research scholar for cyber policy and security at Stanford University, who describes the hacking of Ukraine's air strike alert system as "concerning".

“I think it’s the first time it’s happened to an official Ukrainian information app, but I suspect it won’t be the last,” says Lin, who previously served on former US President Barack Obama’s Commission on Enhancing National Cybersecurity.

“We don’t know how they did it yet… Maybe in the future they’ll be able to do it more but we just don’t know yet.”

Image source, Getty Images

Russia and Ukraine have also exchanged strikes targeting each other's energy infrastructure.

Russia said drone strikes hit an "industrial enterprise" east of Moscow overnight on Saturday, which Ukrainian media identified as the Kstovo oil refinery.

The governor of Russia's Nizhny Novgorod region - home to the Kstovo plant - described a "massive" drone attack during the night and morning.

Gleb Nikitin said significant damage was sustained and warned of power outages and reduced hot water supplies. He said one woman was injured as a result of falling drone debris.

Ukrainian forces have repeatedly attacked Russian oil and gas sites in retaliation for Russian attacks on Ukrainian energy infrastructure.

Ukrainian President Volodymyr Zelensky said Russia had struck energy infrastructure in four regions overnight on Saturday, leaving hundreds of thousands of homes without power. A Reuters report quoted him as saying the intensity of these strikes were "very high".

Some connections were restored on Sunday.

Image source, Getty Images

The fake alert sent to Russia's emergency app had warned users that "nuclear warheads mounted on P1-Suns [a Ukrainian attack drone] had been launched at all regions of Russia".

The alert, which opened with a message telling residents there was a "risk of getting lively" also told them to "stock up urgently on food for three weeks and hide".

Image source, Getty Images

Emergency alert apps in Ukraine and Russia have been hacked, according to reports.

The Ukraine government's Center for Strategic Communications has blamed Russia for the hack in a post on its X account, saying one of the alerts was a "message in Russian about Oreshnik".

A few hours later, Moscow also said that its emergency alert app had been hit by a "massive cyber-attack" - but did not immediately say who might be behind it.

Ukraine's Centre for Strategic Communications has blamed Russia for the hack in a post on its X account.

It posted a picture showing some of the alerts that had showed up on Ukraine's air raid warning app and asked residents to "disregard" any "strange messages" they might see in the app.

Image source, SPRAVDI

The Russian emergencies ministry says its public alert system is "operating as normal", stressing that citizens are informed of alerts through multiple channels including sirens and loudspeakers, text messages, and TV and radio broadcasts, and that the app is "only an additional, ancillary news service".

"The hacking of the mobile app has not had, and cannot have, any impact on the operation of the public alert system," it said on its Telegram channel.

It said specialists were working to restore normal operation of the mobile app but the situation was "under control".

Abdujalil Abdurasulov
Ukraine reporter

The false warnings were sent out just minutes before the end of a ceasefire in the Ukrainian frontline city of Oleshky, which has been under Russian occupation since 2022.

The rare six-day ceasefire had allowed hundreds to evacuate from Oleshky, in a deal that was brokered with the help of US First Lady Melania Trump and Pope Leo XIV.

It was the longest a ceasefire has held since the start of Russia’s full-scale invasion.

But the fighting is likely to resume in Oleshky as both sides have accused each other of using this period to strengthen their frontline forces. And yet, the humanitarian mission has sparked some optimism.

Officials in Kyiv say that it can lead to "systemic solutions" and "pave the way for further steps in the peace process".

Yana Lantratova, who coordinated the Oleshky operation from the Russian side, says that both countries have agreed to carry out "regular humanitarian missions".

But as Vladimir Putin’s spokesperson puts it, the Kremlin sees such operations as separate from the peace process.

Image source, Reuters

The country's air force quickly responded after alarming false alerts on its air raid alert app for a short time said the capital Kyiv was subject to a radiation threat.

"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," the air force said on Telegram.

The Ukrainian Central Intelligence Agency says there was a failure in the Air Alert app, and urges people to use other sources of information to clarify the situation on the threat of air strikes.

The app is supported by the Ministry of Digital Transformation of Ukraine, and informs users instantly about the beginning and end of defence alerts.

Ukraine and Russia are reporting cyber-attacks on their emergency alert apps, with fake warnings sent to users around the countries.

Ukraine was first to report problems, and for a short time the capital Kyiv was subject to a radiation threat, the Ukrainian Air Force has said.

A few hours later Russian authorities said its app was hacked, with a Ukrainian espionage group reportedly sending fake warnings of nuclear strikes inside Russia.

Stay with us as we bring you the latest developments.