Russian President Dmitry Medvedev has signed a decree toughening sanctions on Libya, five months after the UN Security Council imposed them.
Rebels on Friday advanced against strongman Moamer Kadhafi's forces, which a top Nato commander said are no longer able to launch a credible military attack.
As a Security Council member Russia was obliged to toughen sanctions, as specified in Resolution 1973, even though it abstained from the vote because of concerns that it would lead to a full-scale military operation.
But Medvedev has taken his time to do so.
His decree approves a ban on the use of Russian airspace by Libyan planes or non-humanitarian flights to Libya. It also freezes the assets of Kadhafi, his close relatives and entourage, and forbids them from travelling to Russia.
Nato-backed Libyan rebel forces on Thursday advanced on the eastern oil town of Brega and are pushing an offensive at Tuarga in the west. They are also pushing forward in the western Nafusa mountains.
They vowed to take the strategic oil hub of Brega in just "a few days". After a day of fighting, the rebels gained control of part of the residential area of the city late on Thursday.
Rebel forces from the western city of Misrata lanched an offensive on the town of Tuarga, reaching its centre, in an effort to end the barrage of missiles that hits their
Nato's top Libya commander, Canadian Lieutenant-General Charles Bouchard has said that forces loyal to Kadhafi "are no longer able to launch a credible offensive".