The Central Bank said Thursday it did not sell foreign currency on the market on Apr. 1, the first time in five months.
The bank sells foreign currency to support the ruble when the ruble is within 1.95 rubles of the edge of a floating corridor against a dollar-euro basket, which has stretched from 36.25 to 43.25 rubles since March 28.
The absence of market interventions indicated that the ruble had strengthened to the non-intervention range near the middle of the corridor.
At 10.30 a.m. in Moscow on Thursday the ruble was trading at 41.57 against the basket, within the range where the central bank sells $200 million a day to support the ruble.
The ruble has fallen by 8 percent against the basket since the beginning of this year, pushed down by nerves over Russia's role in the Ukrainian political crisis and a larger migration of capital out of emerging markets and into developed economies.