Detailed operational rules for the euro zone's bailout fund, the European Financial Stability Facility (EFSF), are ready for approval of euro zone finance ministers Tuesday, documents obtained by Reuters showed Sunday.

The documents spell out rules of EFSF intervention on the primary and secondary bond markets, in extending precautionary credit lines to governments, leveraging its firepower as well as its investment and funding strategies.

The approval of the rules will clear the way for the 440 billion euro EFSF to attract cash from private and public investors to its co-investment funds in coming weeks, which, depending on interest, could multiply the EFSF's resources.

(Additional reporting by Gernot Heller, Writing by Jan Strupczewski; Editing by Andrew Heavens)