European Economic and Monetary Affairs Commissioner Olli Rehn admitted on Wednesday that Greece’s debt, expected to reach 189 percent of GDP next year, is not sustainable and that the country’s lenders will need to tackle the issue soon, although he ruled out the possibility of an official sector debt restructuring.

“There is no denying that it is increasingly unsustainable without further measures designed for reducing debt,” Rehn said in response to a question from reporters in Brussels regarding Greece’s debt.

He spoke of “four chapters” regarding Greece that need to be concluded in the weeks to come.

“The first two chapters – fiscal and structural – will be voted in the Greek Parliament tonight and over the weekend,” he said in reference to last night’s vote on structural measures and spending cuts, as well as Sunday’s ballot on the 2013 budget. “But beyond that we also need an agreement on financing needs and debt sustainability.”

Speaking to Reuters, however, Rehn ruled out the possibility of the European Central Bank and Greece’s eurozone partners writing down the amounts they are owed by Athens.

“It is important to look at ways and means to reduce the debt burden of Greece. We are currently doing this together with the IMF and the Greek government and it may be a combination of factors related to the length of maturities and level of interest rates of official loans,” Rehn said.

“However, no haircuts of official loans are on the agenda and they are not necessary,” he added.

Rehn said Greece’s lenders were “assessing the financing needs” of Greece should its adjustment program be extended from 2014 to 2016.