"Today I can reveal that we have evidence that Russia and China are collaborating on combat equipment for use in Ukraine," he said in a speech at a London conference.

Shapps warned that NATO needed to "wake up" and bolster defence spending across the alliance.

"US and British defence intelligence can reveal that lethal aid is now flowing from China to Russia and into Ukraine."

He argued that democratic states should make a "full-throated case" for freedoms that are dependent on the international order, meaning "we need more allies and partners" worldwide.

"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.

China and Russia's strategic partnership has only grown closer since the invasion of Ukraine, but Beijing has rebuffed Western claims that it is aiding Moscow's war effort.

China has also offered a critical lifeline to Russia's isolated economy, with trade booming since the invasion and hitting $240 billion in 2023, according to Chinese customs figures.

US President Joe Biden's national security adviser Jake Sullivan, however, appeared to take issue with some of Shapps's comments.

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 United States did though 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.

Chinese President Xi Jinping and Russian counterpart Vladimir Putin put on a strong show of unity during a meeting in Beijing earlier this month.

Xi said in a statement following talks with Putin during his visit that the two sides agreed on the need for a "political solution" to resolve the war.