By Ben Edwards 

MSCI Inc. said it is considering removing VTB Bank's ruble shares from its Russian index after the U.S. Treasury slapped the bank with sanctions restricting its access to U.S. financial markets.

MSCI said it was considering the move on concerns that if VTB issues new equity, it could potentially lead to some market participants trading the shares in the secondary market, breaking those sanctions.

The sanctions prohibit U.S. investors from providing certain firms with financing through new equity or new debt that matures in longer than 90 days.

MSCI said another proposal is to maintain VTB Bank in the MSCI Russia index until the first issuance of new shares. The index provider is seeking feedback from market participants and will announce its decision on Aug. 8.

VTB's Russian peers Rosneft and Novatek GDR won't be removed from the index, MSCI said.

Also Thursday, MSCI said it was launching a new series of composite indexes that will exclude Russia for investors that want to avoid exposure to Russian securities.

Write to Ben Edwards at ben.edwards@wsj.com