Ukrainian state energy firm Naftogaz said on Thursday it held initial talks with creditors on restructuring its $500 million Eurobond due by the end of September and wants an "investor-friendly" solution, according to Reuters.

The ailing energy firm, often at the centre of disputes with Russia of gas prices and supplies, has until Sept. 30 to repay the debt or agree a change to its terms. Some bondholders have already said they would refuse any changes.

"We are exploring ways which will work best for all parties, both investors and for the company. We are focused on finding a solution that is investor-friendly and welcome dialogue with all investors in terms of realising the most effective structure," Naftogaz chief Oleh Dubyna said in a statement.

Analysts have said any forced restructuring of the quasi-sovereign debt -- amounting to technical default -- would have a devastating impact on Ukrainian state and corporate bonds at a time when Kiev would like to borrow more from abroad.

But so far, neither the government nor Naftogaz have indicated they would force a solution, while the International Monetary Fund has given tacit support to agreed changes to the terms.

Russian investors, including the former head of a Gazprom affiliate, have said they plan to block any attempts at restructuring. Corlblow, a Belize-registered company, said investors holding 20 percent of the issue have taken that stance.

Some analysts have questioned why Ukraine would want to restructure the bond after it had received a $3.3 billion tranche from the IMF, which could be used for debt repayment.