MOSCOW, June 20 (Reuters) - The Russian rouble eased

from over-one-year highs against the dollar and yuan on

Thursday, paring some of the previous session's hefty gains amid

low liquidity as markets responded to last week's new U.S.

sanctions on key financial systems.

The sanctions on Moscow Exchange and its clearing

agent, the National Clearing Centre (NCC), led to a range of

varying prices and spreads as trading shifted to the over-the

counter (OTC) market on June 14, obscuring access to reliable

pricing for the Russian currency.

On the interbank market, where liquidity can be low and

major Russian banks that have been sanctioned cannot

participate, the rouble traded 2.1% lower by 0751 GMT against

the dollar at 84.40.

The average dollar-rouble mixed composite rate, calculated

by LSEG and based on data from international brokers and

counterparties, was at 81.92, demonstrating how wide

the spreads - the difference between buying and selling prices -

can now be.

The central bank's official dollar-rouble rate was set at

82.62 for Thursday, calculated on the basis of OTC trading.

The rouble has strengthened sharply since the sanctions were

imposed amid low liquidity, largely caused by various technical

difficulties to do with interbank limits when closing FX deals

on the OTC market.

"The main driver of rouble strengthening is the closing of

foreign currency positions against the backdrop of the halt in

dollar and euro exchange trading, and a general rethinking of FX

investment risks," said T-Investments chief economist Sofya

Donets.

Market imbalance is skewed in favour of sellers of foreign

currency due to restrictions imposed by banks and brokers in the

wake of the sanctions. This has created problems in withdrawing

and using funds, helping to strengthen the rouble.

Against the yuan, the rouble shed 2.2% to 11.44, according

to an analysis of the OTC market.

The yuan had surpassed the dollar to become the most traded

currency with the rouble in Moscow before last week's sanctions

were imposed. It accounted for a 54% share of the FX market in

May.

Brent crude oil, a global benchmark for Russia's

main export, was unchanged at $85.05 a barrel.