The International Monetary Fund is blocking a £10.6bn aid payment to Greece until it receives assurances from European officials on a new Greek bail-out package.
It was thought recent public commitments from the EU stating it would ensure Greece does not go bankrupt were enough to secure the funding, with the IMF due to release £2.9bn, according to the Financial Times.
But amid disagreement over the terms of a new package, the IMF has said it needs firmer commitments before it releases the funds. Both the IMF and European Union are also insisting Greece pass new austerity measures.
Greece must receive the aid before July 15 or it will default on its sovereign debt.
According to the report, IMF acting head John Lipsky says: “That needs to be done before we can move forward and we are hopeful the conditions can be met with alacrity.”