A Russian drone strike on Kharkiv, Ukraine’s second largest city, killed at least seven people overnight – including three children, regional governor Oleh Syniehubov reported.

He said the Iranian-made Shahed drone hit civilian infrastructure in the Nemyshlyan district on the city, causing a massive fire that burned down 15 private houses.

Interior Minister Ihor Klymenko said more than 50 people had been evacuated and that emergency workers had contained the blaze by Saturday morning.

The Ukrainian air force said air defence systems destroyed 23 out of 31 drones launched by Russia overnight.

Russia Ukraine War
Firefighters extinguish a fire after a Russian attack on residential neighbourhood in Kharkiv (Andrii Marienko/AP)

In an online statement, President Volodymyr Zelensky offered his condolences to the relatives of all the victims and said that “terror can’t remain unpunished. Terror can’t remain without a fair response. Terrorists must lose this war they had started. Russia must be held accountable for every life it ruined and destroyed”.

The drones primarily targeted the north-eastern Kharkiv region and the southern province of Odesa, the statement said.

Odesa regional governor Oleh Kiper said four people were injured there by the overnight drone attacks.

The attacks came in three waves, he said. The first targeted the regional capital — the port city of Odesa. All nine drones were shot down, but the debris damaged port infrastructure and injured one person.

The second and the third waves targeted port infrastructure in the Danube river area, Mr Kiper said. A total of 12 drones were shot down and three people were injured.

Romania’s Ministry of National Defence said on Saturday that Russia carried out overnight drone attacks on Ukraine’s river ports of Ismail and Reni, near the border with Romania.

The ministry said that an F-16 jet of the Turkish Air Force was deployed from a Romanian airbase at around 1.15am to carry out “reconnaissance missions” in national airspace to monitor the situation.

Text alerts were also issued to residents in two counties adjacent to the attacks.

Nato member Romania has discovered drone debris on its territory several times before, following sustained attacks on Ukraine’s port infrastructure as Moscow attempted to disrupt Kyiv’s ability to export grain and other produce to world markets.

The Russian Defense Ministry, in the meantime, accused Ukraine of targeting Russia’s civilian transport vessels in the Black Sea with sea drones on Friday evening. One such drone was destroyed, the ministry said, and others were jammed, with no damage to the ships.

The ministry did not say how many sea drones were used or how many ships were targeted. There was no immediate comment from Kyiv’s officials on the alleged attack.