Selling state assets is a key condition of Greece's 240 billion euro rescue package. But the debt-laden nation has so far faced a number of setbacks and has already lowered its 2013 privatisation proceeds target twice, mainly because it did not receive any binding bids for natural gas firm DEPA.

An official from the HRADF privatisation agency, speaking on condition of anonymity, said the court of auditors had raised a series of "technical issues" on the sale of the 28 state assets but added the matter was expected to be resolved soon.

HRADF said it would appeal against the decision to block the deal, which Athens had expected to raise 261 million euros. The delay means Greece raised 960 million euros last year from privatisation proceeds, according to state budget figures.

Eurobank Properties (>> Eurobank Properties REIC S.A.) and real estate company Ethniki Pangaia were picked in October as the preferred bidders for the deal, which Athens had initially intended to complete by the end of 2013.

Both companies have recently attracted hundreds of millions of euros of foreign investment, from Canadian investor Fairfax Financial Holdings (>> Fairfax Financial Holdings Ltd) and private equity firm Invel Real Estate respectively.

Athens has signed 3.8 billion euros worth of privatisation deals since 2011, raising a total of 2.6 billion euros (2.15 billion pounds) in cash.

The asset sale programme demanded by its international lenders, the European Union and International Monetary Fund, suffered a big setback when the sale of DEPA floundered in June after Russia's Gazprom (>> Gazprom OAO), the world's top gas producer and the frontrunner to buy it, withdrew at the final stage.

Greece plans to relaunch the tender for DEPA in 2014, but a high-ranking official warned in December that Athens may not be able to complete the sale due to a lack of investor interest and regulatory obstacles raised by the European Union.

(Reporting by Renee Maltezou and Harry Papachristou; Editing by Gareth Jones)