Greece's Prime Minister Lucas Papademos held talks on restructuring Greek debt with senior officials from the European Central Bank and the European Union after an EU summit on Monday, officials said.
ECB President Mario Draghi was originally expected to attend the meeting but was replaced by Joerg Asmussen, Greek and German officials said. Asmussen, an ECB executive board member, has publicly opposed the ECB taking part in the private sector writedown of Greece's debt holdings.
An ECB spokesman confirmed Asmussen's attendance.
Also at the meeting were Eurogroup Chairman Jean-Claude Juncker, EU Council President Herman Van Rompuy, European Commission President Jose Manuel Barroso, the European commissioner for economic and monetary affairs, Olli Rehn, and Greek Finance Minister Evangelos Venizelos.
It was not clear what was on the agenda, but it was expected to focus on whether the 50 percent reduction in the nominal value of the private sector's holdings of Greek government bonds will be sufficient to restore Athens to debt sustainability.
The Greek government has been in negotiations with banks and insurance companies for several months over plans to exchange their holdings of around 200 billion euros of Greek bonds for around 100 billion euros of longer-dated securities with a lower coupon.
The aim is to reduce Greece's debt burden from around 160 percent of GDP currently to 120 percent of GDP by 2020.
However, the IMF calculates that even with a 50 percent writedown by the private sector, it will not be sufficient to reach the 2020 target. Instead, it may be necessary for the public sector - potentially including the ECB - to take a hit on their holdings.
One EU official played down the meeting, calling it a stock-taking exercise, with the core negotiations going on between the Greek government and the Institute of International Finance, which represents banks and insurance companies.
Van Rompuy told reporters after the summit that the aim was to finalize a deal on a second package of support for Greece by the end of the week, so that all details are agreed by mid-February. Euro zone finance ministers next meet on February 12-13.
Failure to strike a deal on a second package - expected to total at least 130 billion euros of support, depending on the private sector's role - could mean that Athens is unable to meet a 14.5 billion euro bond repayment in March.
(Reporting by Harry Papachristou and Jan Strupczewski, writing by Luke Baker)