Greece's former finance minister Yanis Varoufakis on Wednesday warned that the latest bailout deal was doomed to fail despite Prime Minister Alexis Tsipras saying he was "confident" of ending economic uncertainty.
In a implicit criticism of his former ally Tsipras, he told BBC radio: "Ask anyone who knows anything about Greece's finances and they will tell you this deal is not going to work."
"The Greek finance minister... says more or less the same thing," he added.
The controversial politician resigned the day after Greeks voted against a proposed bailout in a July 5 referendum, accusing the country's creditors of "terrorism."
Varoufakis told the BBC that Germany's veteran Finance Minister Wolfgang Schaeuble had had to "go to the Bundestag and effectively confess this deal is not going to work".
"The International Monetary Fund... is throwing up its hands collectively despairing at a programme that is simply founded on unsustainable debt... and yet this is a programme that everybody is working towards implementing," he said.
Tsipras on Wednesday said he was confident that his debt-crippled nation would secure loan support from a third international bailout which is up for parliamentary approval this week.
"I am and remain confident that we will succeed in reaching a deal and in loan support (from the European Stability Mechanism)... that will end economic uncertainty," he said.
Greece and its creditors are under pressure to finalise a deal by next Thursday when Athens must repay some 3.4 billion euros ($3.8 billion) to the ECB.
Germany on Wednesday said it needed more time to comb through the 400-page text setting out the fiscal and other policy measures Greece must take in exchange for the lifeline.