Ukraine was first to report issues, telling residents to ignore "strange messages". Russia then said its app had been affected. It is not clear if the incidents are connected.

A rare humanitarian ceasefire in Ukraine's Kherson region, that has allowed civilians to evacuate the Russian-occupied city of Oleshky, is due to end on Sunday night. While the localised ceasefire on the front line has held since it was implemented last week, fighting has continued elsewhere.