Volodymyr Zelenskyy said his government is seeking clarification from Beijing after Ukrainian forces captured two Chinese nationals fighting with Russian forces in the eastern Donetsk region.

Zelenskyy said the captured fighters were two of many more Chinese members of the Russian armed forces, and he accused the Kremlin of trying to involve Beijing in the conflict “directly or indirectly”. A few hundred Chinese nationals are thought to have travelled to fight as mercenaries with the Russian army alongside others from Nepal and central Asian countries.

US state department spokesperson Tammy Bruce called the development “disturbing”, adding: “China is a major enabler of Russia in the war in Ukraine.”

Russian forces staged massive drone attacks on the Ukrainian cities of Dnipro and Kharkiv late on Tuesday, triggering fires and injuring at least 17 people, regional officials said. In eastern Donetsk, the focal point of the 1,000-km (600-mile) frontline in the more than three-year-old war, a residential area came under attack in the city of Kramatorsk and local officials said residents were injured. In Dnipro, the attack sparked a fire, damaged houses and cars and injured 14 people, Serhiy Lysak, governor of Dnipropetrovsk region, said on Telegram.

Russia says it is close to regaining full control of its western Kursk region after pushing Ukrainian forces from one of their last footholds there. Russia’s defence ministry released a video of what it said was the recapture of the settlement of Guyevo set to dramatic music, showing smoke rising into the air from various buildings, a soldier waving the Russian flag from the window of a heavily damaged Orthodox church, and Russian troops carrying out house-to-house checks in case any Ukrainian soldiers were hiding. Ukraine officials have not commented on Russia’s claims, but its general staff said in a statement its planes had struck a complex of hangars and military buildings in the region being used by Russian drone operators and maintenance workers.

The US senate has confirmed the appointment of Elbridge Colby as its top policy adviser at the Pentagon, despite concerns he had downplayed threats from Russia and Vladimir Putin. Colby previously questioned whether Russia actually invaded Ukraine, echoing a false Kremlin talking point. After side-stepping repeated questions on whether he believed Russia did invade the country, he was forced to agree it had.

US and Russian delegates will hold talks on Thursday in Istanbul on restoring some of their embassy operations that have been drastically scaled back following Moscow’s invasion of Ukraine, the US state department confirmed.