If Greece's shattered economy was ever to recover, Tsipras said it was crucial that it, too, was also given "a growth clause" that would likewise tie the repayment of Athens' debt load to its ability to pay. "We are also asking for time, a moratorium, of servicing the debt so that we can redirect that money to growth," he said, adding that the suspended interest payments, projected to amount to about €13bn every year, would be used to kick-start the moribund Greek economy. "It would be a win-win solution."

The charismatic politician, catapulted into the spotlight when his party received a fivefold rise in support in elections in June, insisted that the piecemeal approach of international creditors to resolving the crisis would not only destroy Greece but the entire continent.

"There are two pillars to Europe's economic problem, the first being the debt which has to be made viable and the second being austerity which has to finish. If we continue with such measures it is like putting oil on the fire," he said.

Tsipras's economic policies have often been ridiculed by the prime minister, Antonis Samaras, as "dangerous and half-baked". But the 38-year-old left-winger has also been vindicated. Greece's pursuit of austerity in the name of brutal fiscal adjustment has created record levels of poverty and unemployment, trapped it in recession and repeatedly resulted in missed budget targets that have plunged the country into an ever-deeper death spiral. It had opened up bottomless pits in Europe's south that taxpayers in the north were then called to fund.

Although the latest rescue includes a complex bond buyback scheme, which will shave about €30bn from the country's €340.6bn debt pile, it was, he argued, still a case of creditors "buying time" and, as such, was far from adequate.

"When the crisis began in 2009 our debt stood at 120% of our GDP. This year it is projected officially to be 175.6 %. And now they [EU-IMF] say that to make the debt viable we must hit 124% of GDP by 2020," he said, shaking his head in disbelief.

"Let's suppose they are right – but how do they want to get there? After 12 years of catastrophic austerity and measures totalling €19bn Greece will have become a no-man's land."

• This article was amended on 10 December 2012 to correct a reference to Greece's suspended interest payments being €13 per year.