(Reuters) -- Greece has set a March 8 deadline for investors to participate in its unprecedented bond swap aimed at sharply reducing its debt burden, according to a document outlining the offer.

Greece formally launched the bond swap offer to private holders of its bonds on Friday, setting in motion the largest-ever sovereign debt restructuring in the hope of getting its finances back on track.

In the document, Greece said the March 8 deadline could be extended if needed. Athens in the past has said it wants to conclude the transaction by March 12.

The swap is part of a second, 130 billion euro ($175.02 billion) rescue package to claw Greece back from the brink of a default that had threatened to send shockwaves through the financial system and punish other weak euro zone members.

(Reporting by George Georgiopoulos, Writing by Deepa Babington; Editing by Elaine Hardcastle)