Commerzbank's chief executive said on Thursday he expected all Greece's sovereign bondholders to be asked to take a further haircut, including those like the European Central Bank which refused to participate in an earlier debt swap deal.

"We will eventually see another debt haircut on Greece, in which all creditors will have to participate,» Martin Blessing said at a conference in Frankfurt.

In March, Greece averted the immediate threat of an uncontrolled default on its sovereign debt after a large majority of private creditors agreed to a bond swap deal.

At the time, these investors agreed to swallow a loss of about three-quarters on their Greek bonds by swapping them for new 30-year debt paying lower interest rates, a move that cut Greece's debt burden by about 100 billion euros.

The European Central Bank (ECB) declined to participate, arguing that it was not a private sector creditor.

The ECB has spent about 38 billion euros on Greek sovereign bonds with a face value of 50 billion euros. Some of the euro zone's 17 national central banks - the ECB's stakeholders - also hold Greek bonds on their own accounts. It is not known exactly how much they hold, but estimates are around 12 billion euros.

A small minority of private investors also did not participate in the swap deal, and instead prepared for a legal battle over 9 billion euros ($12 billion) of Greek bonds issued under foreign law.

Commerzbank, Germany's second biggest lender, currently has no Greek sovereign exposure, having held bonds worth about 0.8 billion euros at the end of 2011, 3 billions euros at the end of 2010 and 3.5 billion euros at end-2009.

[Reuters]