Telefonica agreed to name Rato, 63, as amember of its advisory boards for Latin America and Europe, for his "experience and career path", it said in a statement.

"He has no executive function and it is a job that does not require exclusivity," a Telefonica spokesman told AFP.

"He will join in the coming days," the spokesman added, saying that Rato would earn a salary but declining to say how much.

Rato served as Spain's economy minister between 1996 and 2004 and then as managing director of the International Monetary Fund until 2007.

He is one of the most prominent financial figures in Spain and a hero of the Spanish right, but has become a target for popular anger since the collapse of Bankia, a major bank that he led.

On December 20 he was questioned by a judge over fraud charges related to the collapse of Bankia, which has become a symbol of Spain's banking crisis.

He resigned as chairman of the bank in May 2012, days before it was bailed out. It has so far received 18 billion euros ($23 billion) in aid from the European Union.