Newly appointed Finance Minister Evangelos Venizelos (R) laughs before a swearing in ceremony, as Foreign Minister Stavros Lambrinidis smiles, at the Presidential palace in Athens June 17, 2011. [Photo/Agencies]

But such a debt rollover would be complex and controversial, financially and legally. Key details have not been worked out, and euro zone finance ministers are expected to discuss them in Luxembourg.

Yields on bonds of indebted euro zone states rose sharply last week as markets speculated Greece might fail to obtain more aid. Many investors think that even if it does, its debt problem is so large that a more radical solution is needed, such as imposing deep losses on its creditors.

The head of Pimco, the world's largest bond fund, said in an interview published on Sunday that Europe risked wasting more money for nothing if it kept pumping billions into the weak Greek economy.

"After a year, every indicator has unfortunately worsened, despite the incredible quantity of financial assistance," Mohammed El-Erian told Italy's Corriere della Sera daily.

"All of this has terrible human consequences and it's associated with a transfer of liabilities from private creditors to European taxpayers. Why? Very little is being done to deal with the excess of public debt, and the conditions for higher growth are not being put in place.

"Further on, if this approach is kept up, more money will be wasted to save private creditors and the risk of a disorderly restructuring of the debt will be greater."