MOSCOW (Reuters) -The Russian rouble weakened to a 10-month low against the dollar during the trading session on Tuesday following Ukraine’s unexpected attack a week ago on Russia’s Kursk region but then rebounded to the day’s opening level.

By 1500 GMT, the rouble was flat at 90.99 to the dollar, according to LSEG data, after falling to 96.60, the lowest level since Oct. 20, 2023. It has lost 6.2% since the start of the attack on Aug. 6.

Trading in major currencies shifted to the over-the-counter (OTC) market, obscuring pricing data, after Western sanctions on the Moscow Exchange and its clearing agent, the National Clearing Centre, were introduced on June 12.

One-day rouble-dollar futures, which trade on the Moscow Exchange and serve as guidance for the OTC market rates, were down 0.4% on Tuesday to 89.60. During the previous day’s trading, the futures lost 2.5%.

The central bank’s official exchange rate, which it calculates using the OTC data, was set at 92.65 for Wednesday, a 3% jump from the rate set for Tuesday.

The weakening of the rouble against the dollar and euro has continued despite support from higher oil prices and increased net daily sales of yuan by the central bank and finance ministry.

According to an analysis of the OTC market, by 1500 GMT the rouble had weakened by 1.3% to 12.07 against the , which has become the most traded foreign currency in Moscow. During the trading the rouble touched 12.11 to yuan, its weakest since June 24.

It was down 0.2% at 99.70 against the euro, according to LSEG data. The central bank’s official exchange rate stood at 96.69 roubles to the euro.

, a global benchmark for Russia’s main export, was down 1.0% at $81.24 a barrel as markets saw reduced risk of a wider war in the Middle East.