European leaders are negotiating a deal that would lead to unprecedented outside intervention in the Greek economy, including international involvement in tax collection and privatization of state assets, in exchange for new bail-out loans for Athens.

People involved in the talks said the package would also include incentives for private holders of Greek debt voluntarily to extend Athens' repayment schedule, as well as another round of austerity measures.

Officials hope that as much as half of the €60bn-€70bn ($86bn-$100bn) in new financing needed by Athens until the end of 2013 could be accounted for without new loans. Under a plan advocated by some, much of that would be covered by the sale of state assets and the change in repayment terms for private debtholders.

Eurozone countries and the International Monetary Fund would then need to lend an additional €30bn-€35bn on top of the €110bn already promised as part of the bail-out programme agreed last year.

Officials warned, however, that almost every element of the new package faced significant opposition from at least one of the governments and institutions involved in the current negotiations and a deal could still unravel.

In the latest setback, the Greek government failed on Friday to win cross-party agreement on the new austerity measures, which European Union lenders have insisted is a prerequisite to another bail-out.

In addition, the European Central Bank remains opposed to any restructuring of Greek debt that could be considered a "credit event" -- a change in terms that could technically be ruled a default. (read more)