Oksana Semenikhina, a customer of Citigroup Inc's Russian unit for the past decade, got an offer from the lender this year that she couldn't pass up.

"They offered to open a rouble term deposit for me at 9 percent interest, through a mobile application," said the 31-year-old marketing manager in Moscow. "Previously, the rate was never higher than 5 percent, and you had to go to the office to do a lot of paperwork."

ZAO Citibank's proposal is part of a wider effort by international lenders in Russia to compete with local rivals for consumer deposits after sanctions sent the rouble plunging last year, spurring rate increases that drove up financing costs for banks and their clients.