Greece and its private creditors said on Saturday they had made progress during talks in Athens on a debt-swap accord needed to lower the country's borrowings and clear the way for a second round of international aid.

"The elements of an unprecedented voluntary private-sector involvement are coming into place," according to an email from Charles Dallara, managing director of the Institute of International Finance, a Washington-based lobby group representing creditors negotiating with the government.

European officials and the nation's private bondholders agreed in October to implement a 50 percent cut in the face value of $259 billion of Greek debt by voluntarily exchanging outstanding bonds for new securities, with a goal of reducing Greece's borrowings to 120 percent of gross domestic product by 2020. An accord with bondholders is key to a second financing package for the cash-strapped country, which faces a $18 billion bond payment on March 20.

"Now is the time to act decisively and seize the opportunity to finalize this historic deal and contribute to the economic stability of Greece, the euro area and the world economy," Dallara said in a joint statement with Jean Lemierre, a special adviser to the chairman of BNP Paribas SA.

A 4 1/2 hour meeting with the IIF officials and Prime Minister Lucas Papademos broke up about 1 a.m. Saturday in Athens. The two sides were in contact by telephone later in the day.

"There's been significant progress," said Hans Humes, president of Greylock Capital Management and a member of the creditor committee. "There's broad agreement about the coupons and structural elements."

The parties were nearing an agreement under which old bonds would be swapped for new securities with coupons averaging between 4 percent and 4.5 percent, said a person with knowledge of the discussions.

Unresolved issues remain, such as whether private investors would be treated differently from official creditors in the event of a later default, said the person. The objective is to reach a deal before the weekend ends.

The two sides, which broke off negotiations on Jan. 13 before resuming them three days ago, have struggled to reach an accord on the coupon and maturity of the new bonds, which would determine losses for investors.

The Financial Times, citing people close to the discussions, reported Saturday that officials from the European Commission, European Central Bank and International Monetary Fund called for an interest rate averaging 3.5 percent on new bonds after private bondholders had already agreed on a 4 percent coupon.

The Wall Street Journal, citing a person with direct knowledge of the talks, said Saturday that discussions may have stalled again as the IMF and Germany pushed for an average coupon of less than 4 percent on the new bonds. IIF spokesman Frank Vogl denied that talks had broken off.