An influential think-tank estimates Greece will need a third package of international bailout loans worth 40 billion euros ($55 billion) to reduce its debt burden to a sustainable level by 2030.

Brussels-based Bruegel said in a study published Thursday that currently discussed plans to only extend the maturity and lower the interest rates on Greece's outstanding debt won't be sufficient.

Greece's European partners and the International Monetary Fund have kept the debt-stricken country afloat since 2010 with bailout loans worth 240 billion euros.

Bruegel says a new loan package would allow the country to gradually reduce its debt level, provided it balances its budget by 2018 and continues to record primary budget surpluses, that is, before counting interest payments.

Greece's debt level currently stands at about 175 percent of GDP.