Belarus's government requested a loan from Russia February 22 due to rises in oil and natural gas prices imported from Russia.
Sergei Storchak said Russia seldom grants such loans but Belarus had received them on two previous occasions.
"Today we should understand how complicated the situation is and how critical the loan is for Belarus," he said.
Storchak said the Belarusian request was somewhat "unexpected" and Minsk will need to give sufficient grounds to the Russian government as the sum will be a serious burden for the budget.
Russia and Belarus were embroiled in an energy dispute earlier this year after Russia doubled the price of gas to $100 per 1,000 cubic meters. In response, Minsk introduced a transit levy of $45 per metric ton for Russian crude oil pumped to Europe via Belarus.
Russia halted deliveries to Europe via the pipeline January 7, saying Belarus was illegally tapping oil following a tit-for-tat price and tariff dispute.
The interruption in supplies affected Germany, Poland, Hungary, the Czech Republic and Slovakia, and further damaged Russia's reputation as a core energy supplier to Europe following a similar energy row with Ukraine involving natural gas in early 2006.
Russia agreed to resume deliveries after receiving a Belarusian government resolution abolishing the transit levy on Europe-bound Russian oil.
The standoff triggered more accusations in Europe that Russia is using oil and gas as a political weapon, and discussions on the need to diversify energy sources.