The world's oldest exchange and largest market for industrial metals has not banned Russian metals from being traded and stored in its system since Moscow invaded Ukraine as there are no Western sanctions on Russian base metals.

It, however, suspended the inflow of Russian metal into its U.S. registered warehouses from late February after the United States announced import tariffs on Russian metal.

U.S. import tariffs have further complicated the use of Russian aluminium produced by Rusal, the world's largest producer outside China.

"Companies in Europe and in some parts of Asia do not want Russian aluminium. They may have contracts so they will take it, but they will not use it and instead deliver it to the LME," an aluminium industry source told Reuters.

A new monthly report by the LME, owned by Hong Kong Exchanges and Clearing Ltd., showed that as of March 31, Russian aluminium amounted to 53% of the total, or 220,575 tonnes, while the share of copper was 49% at 22,275 tonnes and nickel was 21% at 8,058 tonnes.

Russian metal in the LME-registered warehouses accounted for 251,108 tonnes or 44% of the total in March from 42% in February.

(Reporting by Pratima Desai and Polina Devitt; editing by Sharon Singleton)