The Russian government has sent requests to banks seeking proposals (RFPs) on selling stakes in mid-sized oil producer Bashneft, diamond producer Alrosa and state bank VTB, four financial sources told Reuters.

Under pressure from low oil prices, the cornerstone of the Russian economy, the government has been looking for new revenue sources to prevent its budget deficit rising above 3 percent of gross domestic product this year.

The sources said that proposals refer to selling 50.08 percent in Bashneft, 10.9 percent in Alrosa and 10.9 percent in VTB.

Based on current market capitalization, the stakes could fetch 433 billion roubles (US $6.10 billion), Reuters calculations show.

The Federal Agency for State Property Management holds 50.08 percent stake in Bashneft, while 25 percent is held by the Republic of Bashkortostan.

A fifth source, familiar with situation, said that in his understanding that it had been decided that Bashkortostan’s stake in Bashneft was “not to be touched at this point.”

The state property agency did not immediately reply to Reuters written request seeking comment.

The deadline for RFPs is March 21 but does not contain a time limit for any possible sales.