The US has warned four European countries about the methods Russia is using to evade sanctions and provided them with a detailed list of the high-value dual-use goods it is trying to acquire, as Washington steps up efforts to stop Moscow procuring weapons for the war in Ukraine.

Brian Nelson, US Treasury under secretary for terrorism and financial intelligence, visited Switzerland, Austria, Italy and Germany this week on a tour designed to show how Russia is trying to repair its degraded military industrial supply chains by getting round western export controls.

“Russia is throwing a lot of resources at circumventing our sanctions,” a US official said, adding that it was learning from other heavily sanctioned countries such as Iran about how to obtain sensitive technologies through the back door.