“Russian metal warrants issued on or after 13 April 2024 for metal produced before 13 April 2024 are still subject to restrictions that prevent UK LME Members and clients from cancelling or withdrawing the corresponding metal unless they are doing so for the account of a non-UK Client,” the exchange said in a statement.

The CME said: “We are reviewing and will communicate any impact to our markets. We do not disclose the origin or brands of the eligible or registered metal we have in store and that is consistent across all of our physically delivered markets.” On Friday, a UK official said London expected any market disruption to be short-lived and that the government had consulted with colleagues in the US, the LME, the Bank of England and the Financial Conduct Authority to minimize any impact.

The announcement of the ban was made while trading was closed for the weekend. One industry source, speaking on condition of anonymity, predicted price reaction would be muted when trading resumes in Asian time on Monday, while another said a repeat of the kind of aluminum price jump spurred by US sanctions on Rusal in April 2018 was possible.

Both said any European Union sanctions would be almost certain to trigger a price surge. The bloc last year imported around 500,000 metric tonnes of aluminum for use in transport, construction and packaging.