Greece hits back at reports of euro zone 'shock'

Tensions between Greece and its creditors took another turn for the worse this weekend, following a report that euro zone officials were "shocked" at Greece's failure to outline detailed structural reforms and its demands for cash at talks in Brussels last week.

But Greece's finance ministry firmly dismissed the report Sunday, saying it was inaccurate and undermined ongoing negotiations, according to the Athens News Agency.

It comes after German newspaper, Frankfurter Allgemeine Sonntagszeitung (FAS), reported that members of the Euro Working Group (the single currency area's group of deputy finance ministers) said they were disappointed by Athens' lack of reform plans.

Read MoreGreece holds debt sale in scramble for cash

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According to FAS, the sources said Greece's representative asked where the money was "like a taxi driver" and insisted his country would soon be bankrupt, according to Reuters citing the German newspaper.

On Friday, Greece was given six working days by the technical staff of the Euro Working Group to come up with reform plans ahead of a meeting of euro zone finance ministers (the Eurogroup) on April 24. Without reforms, a much-needed last trance of aid from the country's extended bailout program will not be released.

Greece has been the recipient of two bailouts since 2010, worth a combined 240 billion euros ($254 billion). The country's second bailout was extended by four months in February by the bodies overseeing its implementation -- the European Commission, European Central Bank and International Monetary Fund (IMF) -- but there has been a distinct lack of progress on the reform front, testing the patience of its creditors, particularly Germany.

'Final Showdown'

Greece paid a 450 million loan repayment due to the IMF last Thursday, but it has more to pay in the coming weeks and months, and economists are concerned the country will not be able to meet repayments.

"It is difficult to assess just how close Greece currently is to the abyss," Claus Vistesen, chief euro zone economist at Pantheon Macroeconomics, said in a note Monday.

"The country needs to repay the IMF over 2.8 billion euros between now and July, with a 770 million euros instalment due May 12 the next big hurdle. It is difficult to see how the economy can honour its IMF commitments in coming months without some form of aid."

Read MoreGreece: The next deadline approaches

Greece must secure another deal at the next meeting of the Eurogroup, on April 24, Vistesen argued, in order to "carry the economy through a summer littered with repayments" to both the IMF and its EU creditors.

However, the "final showdown" will come in July and August, the economist added, when Greece has to make big payments to the ECB and the European Investment Bank.

- By CNBC's Holly Ellyatt, follow her on Twitter @HollyEllyatt. Follow us on Twitter: @CNBCWorld