At 0940 GMT, the rouble firmed 0.2pc against the dollar at 65.31, heading away from its weakest level since May 3 of 65.60 that it touched soon after the market opening.

Shrugging off a deep drop in oil prices, the rouble recovered after Kremlin spokesman Dmitry Peskov said Calvey, who is being held under house arrest, was a trustworthy businessman.

The Kremlin would like to see him attend Russia's flagship economic forum in St Petersburg later this week but would not invervene in the case.

This case had boosted already lingering concerns about Russia's business climate, prompting prominent representatives of the business elite to speak out in Calvey's favour.

Against the euro, the rouble gained 0.1pc to 72.97 , paring losses along with global benchmark Brent crude oil that added 0.05pc to $62.01.

Still, Brent oil prices remain relatively low as they dropped to $60.55 a barrel on Monday from levels above $70 seen last week.

Russian stock indexes nodded lower at the market opening but then recovered. The rouble-based MOEX Russian index was 1.7pc higher on the day at 2,711.1 after briefly hitting a fresh record high of 2,720.36.

The dollar-denominated RTS index rose 1.6pc to 1,307.2 points.

Shares in Gazprom outperformed by gaining 10pc, which made the Russian gas monopoly number one by market capitalisation.

ON THE RADAR

This week, the market will be watching the annual forum in St Petersburg not only for Calvey's possible appearance but also for trading ideas and for any hints from the central bank on its future monetary policy moves.

Central Bank Governor Elvira Nabiullina will make her final public comments before the rate decision due on June 14.

A Reuters poll showed last week the central bank was widely expected to start its rate-cutting cycle already in June.

Looking forward, the rouble could remain under pressure from Russia's dividend season as many investors prefer to convert rouble-denominated proceeds into foreign currencies.

According to ING Bank estimates, around $9 billion worth of dividends could be converted into FX out of 2 trillion roubles ($30.54 billion) that Russian companies should pay in May-August.

The rouble's upside is also limited by state FX purchases that are set to increase slightly in June, according to a Reuters poll.