The Kremlin on Tuesday repeated its claim that Ukraine plans to use a radioactive "dirty bomb", warning the West it was dangerous to dismiss Moscows position. Ukraine, the United States, Britain and France have all rejected Moscows claims - voiced by several officials in recent days - that Kyiv could be preparing to detonate a radioactive device in Ukraine. In a briefing call with reporters, Kremlin spokesman Dmitry Peskov said this was a foolish approach given the gravity of the situation. Moscow has provided no evidence for its claims. "This is an approach that is far from serious," Peskov said of the United States dismissal of Moscows claims. "This is an approach that is not permissible against the background of the seriousness of the danger we are talking about ... Once again, we emphasize the great danger that lies in the implementation of Ukraines plans related to a dirty bomb," he added. A "dirty bomb" is an explosive device laced with radioactive material. Russia intends to raise the issue at the United Nations Security Council later and has urged UN chief Antonio Guterres to do all he can to "prevent this heinous crime from happening." Washington and other Western countries have accused Russian President Vladimir Putin of using the alleged dirty bomb threat as a pretext to escalate the war in Ukraine.