The International Monetary Fund has said it is prepared to do more to tackle the eurozone debt crisis, but also warned there may not be enough funds to bail out larger economies such as Italy.
Speaking in Washington, IMF Managing Director Christine Largarde said current lending obligations can be honoured, but this could change.
There have been reports that the G20 countries are preparing a €3 trillion eurozone rescue package with the possibility of a Greek default remaining the source of the greatest anxiety.
Ms Lagarde warned, however, that eurozone countries needed to do a lot more.
Greek Finance Minister Evangelos Venizelos sought to reassure nervous markets and EU partners last night by pledging that his government would do whatever it takes to avoid default and stay in the eurozone.
After meeting his German, French, Italian and Belgian counterparts, Mr Venizelos dismissed any talk of Greek bankruptcy.
Meanwhile, Portugal, going through a deep recession, is moving "quickly and resolutely" to fix its shaky finances and reform its economy, Prime Minister Pedro Passos Coelho told the United Nations.
Lisbon is enacting tough austerity measures to meet the terms of a €78bn bailout from the EU and IMF.
Portugal was the third eurozone member to receive rescue funds after Greece and Ireland.
"As widely recognised, we are moving quickly and resolutely to consolidate our public accounts and to implement structural reforms to modernise our economy and promote economic growth and employment," Mr Passos Coelho told the UN General Assembly yesterday.
"We view the crisis as an opportunity to adapt our economic model and to strengthen the Portuguese economy."
Portugal's recession is expected to last through next year and unemployment is at its highest levels since the 1980s as the government raises taxes and cuts spending to meet budget deficit targets.
The government has to cut the deficit to 5.9% of gross domestic product this year from 9.1% in 2010.
