Greece\'s five biggest banks said they would take part in the country\'s debt buyback which expires on Friday, putting Athens on track to meet targets set by international lenders. The buyback scheme, in which investors had to declare their interest by Friday (07.12.2012), is central to efforts by Greece\'s eurozone and International Monetary Fund lenders to cut its debt to manageable levels and unlock much needed aid for the country. The country\'s biggest lenders - National Bank, Alpha, Eurobank, Piraeus bank, and Hellenic Postbank - each said they had approval to participate, but did not specify how much of their sovereign debt holding they would tender. The smaller Attica Bank also said it would take part. National Bank of Greece\'s announcement came hours before the 5pm GMT deadline for private sector bondholders to join the scheme, under which they would sell back their devalued Greek debt holdings to the government. A Greek official said Athens would not make any announcement until Monday on the interest it had received. Under the scheme, Athens aims to spend 10 billion euros ($13 billion) of borrowed money to buy back bonds far below their nominal value, in a bid to cut debt by a net 20 billion euros. Banking sources earlier said the banks had asked their boards to approve selling back as much as their entire holdings. Smaller Attica bank\'s board also approved participation. The buyback is the latest in three years of eurozone efforts to resolve Greece\'s problems. The economy has shrunk by 20 percent in the last five years and unemployment has hit a record 26.2 percent, pushing public anger to new highs. Athens has pressured its banks, which hold an estimated 17 billion euros ($22 billion) out of the 63 billion in eligible bonds, to sell and they had been expected to do so since they depend on bailout funds that a successful buyback would unlock. Analysts said the better-than-expected terms announced by Athens earlier this week would draw enough foreign investors as well, ensuring success.