Washington imposed sanctions on some of Russia's biggest companies and businessmen, including London-listed En+, on April 6, striking at allies of President Vladimir Putin to punish Moscow for alleged meddling in the 2016 U.S. presidential election and other so-called malign activities.

En+ manages the aluminium and hydropower businesses of Russian businessman Oleg Deripaska.

The LSE has postponed the suspension of En+ GDRs before, but this time it did not say whether a suspension would take effect at a future date.

"The Exchange will not suspend the trading of En+ Group GDR... on Friday 1 June 2018," it said in a statement.

"The Exchange will continue to monitor the situation and is in communication with the UK authorities."

(Reporting by Alistair Smout and Polina Ivanova. Editing by Jane Merriman)