German Chancellor Angela Merkel has said she can only discuss further aid for Greece after EU and IMF officials report on the implementation of its existing rescue plan.

Speaking to foreign correspondents in Berlin, Merkel did not rule out additional funding for Athens, or a possible further easing of terms on its €110 billion bailout, and she voiced confidence that the German parliament would back a permanent bailout mechanism for the euro zone.

'I need to analyse the findings of the European Central Bank, European Commission and International Monetary Fund first and I can't comment before that,' she said. 'Anything else would not help Greece or Europe.'

A source with direct knowledge of the joint inspection mission visiting Athens said EU and IMF officials had not yet concluded whether Greece had met targets required to receive the next tranche of aid under its existing aid deal.

He stressed the inspectors were not discussing a new bailout package with the Greek government, which has acknowledged it may not be able to return to capital markets next year as planned.

A euro zone source in Brussels said Greece first needed to show credible progress on meeting agreed targets for fiscal consolidation and privatisation of state assets before further emergency funding could be considered.

German Finance Minister Wolfgang Schaeuble told conservative lawmakers that fresh assistance to Greece could involve further extending loan repayment periods and cutting interest rates, participants at the closed-door meeting said. Schaeuble also vehemently rejected calls by Eurosceptical critics for Greece to leave the euro zone, saying 'everything would be better than an exit.'

French Economy Minister Christine Lagarde, asked about more aid for Greece on a visit to Zurich, said: 'We have been rescuing for a year and we will keep up.' She gave no details.

In Strasbourg, EU Monetary Affairs Commissioner Olli Rehn said it was premature to talk about a new package for Greece now but he expected a decision in a few weeks' time on the next steps to tackle Athens' refinancing needs.