Russian companies involved in the oil and oil products business are transferring their accounts from Russian banks hit by U.S. and EU sanctions to other financial institutions, including Rosbank, Unicredit and Raiffeisenbank, five Reuters sources familiar with the situation said.

The U.S. has imposed sanctions on five key Russian banks, including major state banks VTB (MCX:VTBR) and Sberbank (MCX:SBER), which have been widely used to finance oil, gas projects and Russian energy trading.

The West is imposing mounting sanctions against Russia for its invasion of Ukraine, which began last Thursday. Russia calls its actions a special operation to “demilitarize and denazify” the neighboring country.

The imposition of sanctions on Russian banks led to the suspension of payments to their Russian customers as Western banks stopped working with the listed financial institutions.

“We have not been able to receive payments from our counterparties to accounts in the sanctioned banks since last week, so we had to make changes to continue working,” a source in the Russian oil industry told Reuters.

Rosbank, Unicredit and Raiffeisenbank did not provide prompt comment to Reuters’ written requests.

The United States and its allies took action on Saturday to block some Russian banks’ access to the SWIFT international payment system in a move to increase pressure on Mos.