The trading arm of Russia’s gas giant Gazprom PJSC is under increasing pressure as clients and peers flee in response to the war in Ukraine, posing a risk for energy markets from the U.K. to Germany and Singapore.

Gazprom Marketing & Trading is facing liquidity problems as banks delay its transactions and peers refuse to deal with it, according to people familiar with the matter. But its failure would upend markets beyond its U.K. domicile: The firm is one of Europe’s top gas and power traders, has units in Asia and North America, and traded more than 100 liquefied natural gas cargoes in 2020.

Little known to the general public, Gazprom Marketing & Trading has revenues almost on par with the trading arm of Centrica PLC, the U.K.’s top energy supplier. If it goes out of business, it would bring down its U.K retail arm, a supplier to the National Health Service. The threat is so acute that the government made plans to nationalize the business, known as Gazprom Energy.