Greece needs another 10 billion euros ($13.1 billion) by September to plug a funding gap which could threaten the disbursement of further aid, German newspaper Sueddeutsche Zeitung cited a senior official from the European Commission as saying Wednesday.
The international funds for highly-indebted Greece are insufficient to help the country to emerge from the crisis, the paper said. Immediately after the summer recess, euro countries would need to discuss further financing for the Greek program, a senior European Commission told the Sueddeutsche Zeitung.
The report comes just ahead of a trip to Athens by the German Finance Minister Wolfgang Scheauble on Thursday. With German elections due in September 22, it is unlikely that the German minister can commit to more aid, the paper added.
(Read More: Greece MayReach Surplus by End of 2013: Lagarde)
Athens ground to a halt on Tuesday as Greek workers went on strike in protest at thousands of planned public sector job cuts, ahead of the visit.
A spokesperson from the European Commission declined to comment on the report.
Greece has received tens of billions of euros in loans from its euro zone partners and the IMF since mid-2010 to avert bankruptcy. A funding gap has emerged however, which will need to be plugged in order to secure further IMF loans.
Under IMF rules, loan programs need to be fully financed for a 12-month period or the IMF withholds loan disbursements.
- By CNBC's Holly Ellyatt, follow her on Twiter @HollyEllyatt