The Spanish government has decided to postpone the privatisation of airport operator AENA via a share listing until the first months of 2015.

According to sources, the transaction is postponed until a technical flaw that was identified can be resolved. The "flaw" is that a tender process was not used to pick the auditor to sign-off the comfort letter needed for the prospectus. Sources said a tender would be held shortly to pick a new auditor.

The partial sale of AENA had promised to be the largest share sale in Europe this year.

AENA is the world's leading airport manager, moving 187.4 million passengers in 2013. The company runs 46 airports and two heliports in Spain and another 15 airports abroad, most in Mexico. The four stand-out airports in AENA are Madrid, Mallorca, Malaga and Barcelona.

Spain's government now has a window of around six months to try and reactivate the IPO, or else it faces starting from scratch again.

Several weeks ago, AENA selected three core investors that will acquire minority stakes in the privatization. An initial 21 percent stake would be sold to three shareholders, Corporacion Financiera Alba, Ferrovial and Britsh fund The Children's Investment Fund (TCI).

These three are committed to going ahead provided the sale is completed by April 16 including the IPO.

The price at which the three offered to buy into the airports operator valued it at between €7.3 billion and 8 billion, higher than originally anticipated.

Based on these figures and including debt of €12 billion, AENA would have an enterprise value of €18.2-20 billion, or 11.7 - 12.8 times its 2013 EBITDA. That's higher than Germany's Fraport (10.7 times EBITDA) and France's ADP (10.5 times EBITDA).