MOSCOW, Dec 5 (Reuters) - Moscow Exchange, Russia's largest bourse, said on Tuesday it would halt trading in the U.S. dollar should sanctions be imposed, after Washington targeted another Russian exchange, SPB, with restrictive measures last month.

The U.S. Treasury in early November targeted SPB, Russia's second-largest stock exchange as part of sweeping new measures that also aim to curb Russia's future energy capabilities and sanctions evasion. Some Russian market players believe Moscow Exchange could be targeted next.

The sanctions forced SPB, which specialises in trading foreign shares, to halt trading of shares on its exchange and tweak its strategy to focus on settlements in roubles. More than two thirds of clients' foreign currency funds are now blocked.

"The U.S. dollar will not be traded if there are American sanctions, but it no longer plays such a role in the structure of the exchange's FX market (as it used to)," Igor Marich of Moscow Exchange told reporters.

"The central bank in this case can count on the official exchange rate on over-the-counter transactions."

The USD/RUB currency pair accounted for 78% of trading on Moscow Exchange in the first quarter of 2022. In October-November 2023, its share of trading was 32%, exchange data showed.

Meanwhile, China's yuan has become the largest player. From a share of 1% in early 2022, CNY/RUB now accounts for 43% of trading on Moscow's FX market. (Reporting by Elena Fabrichnaya; Writing by Alexander Marrow; Editing by Susan Fenton)