Greek main opposition leader Antonis Samaras rejected on Tuesday of European Union\'s (EU) demand that Greek political leaders sign a written commitment to fully implement bailout package sealed last month. \"This is an issue of national dignity. I have repeatedly explained why, in order to protect the Greek economy and the European common currency, the implementation of the October 26 agreement has become inevitable. I will not allow anyone to doubt my word,\" said Samaras in a statement released by his office. Samaras\' statement came as an answer to EU Commissioner for Economic and Monetary Affairs, Olli Rehn, who has asked Greece for a written letter of commitment on the deal as a precondition for the release of the sixth tranche of aid loans to Athens in November. The letter, according to Rehn, should be signed by the outgoing Prime Minister George Papandreou and Samaras, as leaders of the two main parties have been negotiating a coalition government, in addition to the signatures of the new prime minister, the new minister of finance and the governor of Bank of Greece. The disagreement could delay the ongoing negotiations for the formation of an interim government that will lead Greece to early national elections.