By Darya Korsunskaya and Gleb Bryanski

(Reuters) - Russia will buy foreign currency on the market in the coming month for the first time since ‌the war in Ukraine, a Finance Ministry statement said on Wednesday, as high oil prices caused by the Iran war have boosted Moscow's revenues from crude exports.

The Finance Ministry said it will buy forex worth 110.3 billion roubles ($1.46 billion), mostly Chinese yuan, from May 8 to June 4 for the National Wealth Fund, which ​is used to stabilise the budget. The move should also prevent the rouble from excessive strengthening.

However, the rouble was up ​by 0.9% against China's yuan in trading on the Moscow exchange after the announcement, as traders and ⁠analysts had expected the government to buy foreign currency more aggressively.

The central bank will carry out the purchases. When netted against the ​central bank's own operations, the state's net forex purchases will amount to 1.18 billion roubles a day compared to current sales of 4.6 ​billion roubles a day.

FEWER PURCHASES THAN ANALYSTS EXPECTED

"The volume of currency purchases turned out to be significantly lower than expected, we had forecast 14–18 billion roubles per day," said T-Investment's chief economist Sofya Donets.

"This may indicate that the oil and gas revenues of the budget, from which the volume is calculated, were ​not as high in April as the prices of Russian oil would have allowed us to expect," she added.

Analysts linked the lower ​volume of windfall revenues to Ukrainian drone attacks on ports and refineries that forced Russia to cut its oil output in April, limiting its ability to ‌benefit from ⁠a rise in international oil prices to well over $100 a barrel.

Many forecasters had said Russia could be among the main beneficiaries after U.S. and Israeli attacks on Iran, which began at the end of February, led to a blockade of the Strait of Hormuz and unprecedented disruption of energy supplies.

Under Russia's budget rule, the government buys foreign currency for the wealth fund with tax revenues collected when oil prices ​exceed a certain cut-off point, ​currently set at $59 per barrel.

RUSSIAN ⁠OIL PRICES WERE DISCOUNTED BECAUSE OF SANCTIONS

If oil trades below that cut-off price, the government sells forex from the fund to cover the budget deficit. The ministry suspended operations for the fund in February ​when prices for Russian oil were low because of sanctions-linked discounts.

The decision to suspend the transactions ​was aimed at preventing ⁠the fund from depletion.

However, when oil prices soared after the closure of the Strait of Hormuz, many analysts questioned the logic of the move that kept the rouble overvalued.

The ministry said earlier it would take into account deferred transactions for March, when it would have sold forex, ⁠and April, ​when determining May volumes. Deferred sales for March would offset purchase volumes, softening the ​market impact.

Russian state oil and gas revenues fell 21.2% year-on-year in April to 855.6 billion roubles ($11.32 billion), according to finance ministry data published also on Wednesday, but were ​up from 617 billion roubles in March.

($1 = 75.6000 roubles)