At least six people have died in a Russian drone attack on the Ukrainian city of Kharkiv, local officials say.Mayor Ihor Terekhov said Iranian-made Shahed drones had hit several buildings, including apartment blocks, early on Saturday.Attacks on Kharkiv, the closest big city to the Russian border, have been intensifying in recent weeks.Ukrainian officials have said the city might be the target of a future Russian offensive."This attack on peaceful residents of Kharkiv once again proves that Russia is a terrorist state," Mr Terekhov wrote on the Telegram messaging app. At least 10 people were injured by the attack, he added.Unverified photos published by Ukrainian police showed rescuers at the scene, with damaged and burning buildings visible.

On Thursday, Russian forces attacked Kharkiv with drones, leaving at least four dead, according to Ukrainian officials.And on Friday, authorities said four people were killed and over 20 wounded in missile strikes on the southern city of Zaporizhzhia.