The Interfax news agency quoted a military source as saying that Russia had an order book for contracts from Libya worth $2.0 billion while negotiations had been in progress for deals worth $1.8 billion more.
"Among the countries of the Middle East and North Africa, Libya is one of the main buyers of Russian weapons," the source, which was not identified, told the agency.
"As of today, contracts for military hardware of around $2.0 billion had been agreed with Libya.
"Work on contracts for aviation equipment and air defense was also in the final stage. These were valued at $1.8 billion," the source said.
Russia was initially slow to echo Western condemnation of Kaddafi amid his bloody crackdown on an uprising but on Saturday it joined other UN Security Council members in ordering an arms embargo against Libya and other sanctions.
Another report last week said Russia could lose a total of up to $10 billion in arms sales from the wave of unrest currently destabilizing regimes in North Africa and the Middle East.