Russia spent 352.5 billion rubles ($11.97 billion) from its oil wealth funds in April, using the money to plug a post-recession budget deficit and boost the state pension coffers, Finance Ministry data showed on Tuesday.

The Reserve Fund fell to 1.19 trillion rubles on May 1 from 1.55 trillion rubles a month earlier, dented by a transfer of some 350 billion rubles into the budget and, to a lesser extent, by the appreciation of the ruble against foreign currencies in which the cash is kept.

In dollar terms, the fund's value fell to $40.6 billion from $52.9 billion, based on the average exchange rate for the month.

The Reserve Fund — accumulated during nearly a decade's worth of oil-fueled economic boom — is now propping up the budget, which slipped into the red in 2009 as Russia's gross domestic product suffered its biggest contraction in 15 years.

The National Welfare Fund fell to 2.6 trillion rubles ($88 billion) from 2.63 trillion rubles a month ago.