Greece will seal a deal to write-down a major part of its debt held by private creditors in the next two weeks, the head of the main labour union said on Wednesday after talks with the prime minister. \"The negotiation with creditor representatives is going well. There will be a deal in the next 15 days, but another month will be required to implement it,\" Yiannis Panagopoulos, head of the private sector GSEE union, told reporters. A group representing private bond holders agreed with eurozone leaders at a European Union summit in Brussels in October to erase up to half the face value of the Greek debt they hold, reducing its debt by approximately 100 billion euros ($130 billion). The Institute of International Finance, which represents more than 450 financial institutions worldwide, on Tuesday said negotiations had made headway, adding that it was \"essential\" to reach agreement in the coming days. But media reports have indicated there is pressure from Greece\'s international bailout partners on private creditors to accept a greater so-called \"haircut\". The result of the negotiations will be a key determining factor for the eurozone countries and the International Monetary Fund on possible further assistance to the debt-wracked eurozone country. Athens is seeking a second rescue, in addition to the 110-billion-euro programme it was awarded by the EU and IMF in May 2010.