Greece said Thursday another 20.27 billion euros ($26.7 billion) in government bonds would be exchanged next week under a landmark bond swap that has already erased nearly a third of its debt. And Athens also extended the deadline for the final phase of the operation -- already postponed twice -- to April 20. \"The Hellenic Republic today announced its intention to complete on April 11 the exchange of an aggregate principal amount of 20.27 billion euros\" in bonds and state utility loans guaranteed by Greece under foreign law, the finance ministry said in a statement. The ministry added that holders of equivalent bonds who had not yet joined the initiative would have until 2200 GMT on April 20 to decide. The first phase of the swap, involving bonds issued under Greek law, was completed on March 12, cancelling more than 94.8 billion euros in near and mid-term debt in return for cash incentives and longer-term maturities. Debt holders are given new bonds with a face value equivalent to 31.5 percent of the face amount of the debt exchanged, plus 24-month notes from the European Financial Stability Facility, the eurozone\'s current rescue fund. Holders also receive detachable securities linked to Greek output with a notional amount equal to the face amount of the new bonds. The Greek bond swap is intended to help Greece meet a wave of debt repayment deadlines this year and is a key part of a eurozone-IMF rescue to enable the country to rebuild its economy. Greece has a total public debt of over 350 billion euros. Greece received 73 billion euros under a first EU-IMF bailout that began in 2010 and has agreed a second rescue programme worth 148 billion euros. The prospect of yet another lifeline has not been ruled out altogether.