European leaders' delay in hammering out a solution to Greece's debt problem is harming the country's economy and upsetting international markets, the Greek prime minister said ahead of a European Union summit in Brussels on Thursday.

“I am not worried about the tranche, but each day that passes without a final decision is bad for the economy, for morale, and for the markets,» Antonis Samaras told journalists.

“I will not let the sacrifices of the Greek people go to waste,” he added.

A marathon meeting between eurozone ministers and International Monetary Fund Managing Director Christine Lagarde earlier this week did not produce an agreement either on the disbursement of up to 44 billion euros in loan tranches Athens is expecting next month, nor on how to reduce its runaway debt.

The failure to reach a deal was seen as a blow to the conservative-led coalition, which had argued that the austerity package passed this month would lead to both issues being resolved.

Samaras, who is in Brussels for an EU summit on the 27-member bloc's budget, was to hold talks with Eurogroup chief Jean-Claude Juncker and European Council President Herman Van Rompuy.

Reports suggested Samaras might also meet with German Chancellor Angela Merkel.

A German official on Thursday said that EU leaders were likely to discuss Greece's debt crisis on the sidelines of the summit.

“Greece is not on the agenda of the summit, but I expect it could be a topic in conversations between the leaders,” Reuters quoted the official as saying.