Joe Biden’s administration has challenged a claim by the British defence secretary, Grant Shapps, that China is sending “lethal aid” to Russia for use in its war in Ukraine. Speaking on Wednesday, Shapps cited “new intelligence” that suggested Beijing was giving Moscow deadly “combat equipment” for the first time. On Thursday, the Ministry of Defence in London said it would not give further details. Russia has begun a new offensive in Ukraine’s north-east and relentlessly targeted Kharkiv, Ukraine’s second city, with missiles and glide bombs. On Thursday, a strike on a printing house in the city killed seven and injured many more. Previously, China has been accused by Washington of providing critical components used by Russia’s military since its 2022 full-scale invasion of Ukraine. These include microelectronics that have been fitted in tanks, missiles and other weapons. Shapps’s comments at the London Defence Conference went further. “Today I can reveal that we have evidence that Russia and China are collaborating on combat equipment for use in Ukraine,” he said. Calling for Nato to “wake up” and bolster defence spending alliance-wide, he added: “US and British defence intelligence can reveal that lethal aid is now flying from China to Russia and into Ukraine. “And this is new intelligence, which leads me to be able to declassify and reveal this fact today. I think it’s quite significant.” Shapps did not provide evidence to support his assertion. But he said there had been a 64% increase in trade between the countries since the start of the war in Ukraine and that they were “covering each other’s back”. “It’s time for the world to wake up. And that means translating this moment to concrete plans and capabilities. And that starts with laying the foundations for an alliance-wide increase in spending on our collective deterrent,” he said. After its failure two years ago to seize the Ukrainian capital, Kyiv, the Kremlin sought military supplies from authoritarian partners. It sourced “kamikaze” drones from Iran and artillery shells and short-range ballistic missiles from North Korea. Some of these missiles have been used in Moscow’s bombardment of Kharkiv. Biden’s national security adviser, Jake Sullivan, appeared to take issue with Shapps’s remarks on Beijing’s alleged role. He said the possibility that China might “provide weapons directly – lethal assistance – to Russia” had been a concern earlier, but that “we have not seen that to date”. The US did, however, have a “concern about what China’s doing to fuel Russia’s war machine – not giving weapons directly, but providing inputs to Russia’s defence industrial base,” he added. A spokesperson for the Chinese embassy in London dismissed Shapps’s assertion as “totally groundless” and accused Britain of spreading “baseless accusations”. China and Russia’s strategic partnership has grown closer since the invasion of Ukraine and Beijing’s purchase of oil and gas has helped boost the Russian economy. The Chinese president, Xi Jinping, welcomed his Russian counterpart, Vladimir Putin, to Beijing this month, where the two leaders put on a show of unity. Xi said in a statement after the talks that they had agreed on the need for a “political solution” to resolve the war. Last month, Julianne Smith, the US ambassador to Nato, told Politico that China was continuing to sell related supplies such as drone technology and gunpowder ingredients to Russia. “The PRC [People’s Republic of China] cannot claim to be entirely neutral in this case, they are in fact picking a side. “If they were not providing some of these components, or this materiel support, Russia would be in a very different situation and would have trouble pursuing some of these acts of aggression,” she said. On Thursday, Russia launched 15 missiles including one that hit a printing house and killed seven people. Oleh Syniehubov, the regional governor, told reporters at the scene: “There are no military facilities either here or nearby.” The strike also led to the destruction of thousands of books. Ukrainian authorities said the strikes came from Russia’s Belgorod region. Kyiv has in recent weeks been lobbying Washington for permission to use US-provided weapons to hit targets inside Russia. The Biden administration has so far been reluctant to agree, fearing escalation, but may be moving towards changing its mind, swayed by Kyiv’s argument that it is impossible to protect against the strikes on Kharkiv and other cities without hitting targets across the border. Ukraine’s president, Volodymyr Zelenskiy, said in a social media post on Thursday that the country’s shortage of air defence systems and lack of ability to hit inside Russia was hampering the country’s defence. “This weakness is not our weakness, but that of the world’s, which for the third year already has not dared to deal with the terrorists exactly as they deserve,” he said.