MOSCOW: The rouble opened steady on Thursday, boosted by rising oil prices but geopolitical risks linked to the imprisonment of Kremlin critic Alexei Navalny cast a shadow over the Russian currency's efforts to strengthen.

At 0730 GMT, the rouble was 0.3% stronger against the dollar at 75.71 and had gained 0.5% to trade at 90.90 versus the euro.

Brent crude oil, a global benchmark for Russia's main export, was up 0.7% at $58.96 a barrel, earlier hitting its highest mark since February 2020.

The rouble has come under pressure in recent weeks over Navalny's case, with widespread protests and condemnation from western leaders raising the risk of fresh sanctions against Moscow.

A court on Tuesday sentenced Navalny, a prominent opponent of President Vladimir Putin, to three and a half years for alleged parole violations.

Wednesday's official extension of the New START nuclear pact, the last major arms control treaty between the United States and Russia, toned down recently revived arms race concerns, said BCS Global Markets.

"Still, the noise of sanctions out of the US continues, which dampens sentiment and is likely to temper the Russia risk trade," BCS added.

The rouble should soon gain support from the reduced foreign currency purchases by the finance ministry, which begin on Friday.

Russian stock indexes edged higher.

The dollar-denominated RTS index was up 0.6% to 1,395.4 points. The rouble-based MOEX Russian index was 0.4% higher at 3,355.2 points.