Leading eurozone policy-maker Jean-Claude Juncker said Tuesday that a "soft restructuring" of Greece's 330-billion-euro debts is a possibility as an EU-IMF mission in Athens was extended by one week.

Luxembourg Prime Minister Juncker told a finance conference in Brussels that coincided with a second day of European Union talks on the recurrent Greek crisis, that a re-negotiation of Greek debt was gradually coming into play.

But experts on a mission in Athens first will seek to obtain details on Greek government plans to privatise state assets. The EU and IMF have demanded Athens raise 50 billion euros via a massive sale of state-owned ports and other facilities so as to restore its public finances to health.

"If Greece makes all these efforts, then we must see if it is possible to make a soft restructuring of Greek debt," Juncker said at the conference.

At the same time, he added: "I am strictly opposed to a major restructuring of Greek debt."

EU Economic Affairs commissioner Olli Rehn said Athens had committed to closing gaps in its budget targets "in the coming days," having already taken painful measures to save 20 billion euros ($38 billion) in the 12 months since its 110-billion-euro bailout last May.

Rehn claimed Greece could reduce its public debt by more than 20 percent of Gross Domestic Product by 2015 if the 50-billion-euro sales target is achieved and termed the privatisation programme the "cornerstone of recovery."

Fifteen billion euros was supposed to be raised this year and next under the existing EU-IMF programme bailout plan, Rehn noted.

He called on Greek opposition parties to put aside their differences and fully back "decisive steps in the coming days" that he said are "indispensable before the Eurogroup can look into further steps possible to ensure that Greece is on a sustainable path."

The EU-IMF experts were expected to report back in early June to flesh out scenarios mapped out at this week's ministerial talks ahead of a full summit of European Union leaders on June 24.

German Deputy Finance Minister Joerg Asmussen said the expert mission, scheduled to end Wednesday, would probably require an additional seven days.

Diplomats stressed Tuesday that Greece has made "zero" progress, with planned sell-offs for the three months to end-June already put back into the second half of the year.

"Soft" debt restructuring is understood as lengthening repayment schedules and easing interest rates paid on the debt.

A so-called "hard" restructuring is considered to mean states writing off a part of their debt, the route followed by Argentina or Mexico among the more notorious defaults in the recent past.

Economic experts believe an outright default could have serious repercussions for the whole of the eurozone where Ireland and Portugal have also had to be bailed out after Greece sought help in May last year.

Greece's debts are currently running at more than a year-and-a-half of all the country's economic output.