India's oil trade, in response to the turmoil of sanctions and the Ukraine war, provides the strongest evidence so far of a shift into other currencies that could prove lasting.
MTS had facilitated some Indian oil non-dollar payments, the trade sources said.
An Indian refining source said most Russian banks have faced sanctions since the war but Indian customers and Russian suppliers are determined to keep trading Russian oil.
"As it is, the government is not asking us to stop buying Russian oil, so we are hopeful that an alternative payment mechanism will be found in case the current system is blocked."
Similarly, many banks from Russia have opened accounts with Indian banks to facilitate trade.