The Spanish newspaper El Pais apologized on Thursday for splashing a false photo of Venezuela's cancer-stricken leader Hugo Chavez on its front page, prompting a furious response from Caracas, which vowed to take legal action.

Within minutes of posting the image online as a global exclusive, El Pais said it had discovered from social media that the photo was not of Chavez. It removed it from its website and withdrew its print edition.

Venezuela's government said the publication of the photo - which showed the head of a man lying down with a breathing tube in his mouth - was grotesque, while Argentinian President Cristina Fernandez, a close ally of Chavez, called it vile.

"El Pais apologizes to its readers for the damage caused. The newspaper has opened an investigation to determine the circumstances of what happened and the errors that were committed in the verification of the photo," the paper said.

Chavez, 58, is fighting to recover in Cuba after undergoing his fourth cancer operation in just 18 months.

El Pais, one of the world's biggest Spanish-language publications, said it received the grainy image from the agency Gtres Online.

El Pais said in a statement that the newspaper was told the photo had been taken seven days earlier by a Cuban nurse who was part of Chavez's medical team and was then sent to the nurse's sister, who lives in Spain.

"The agency has acknowledged it was deceived by those who provided the material and will take legal action," El Pais said.

Venezuela said it will take appropriate legal action, and that the newspaper's apology to its readers was not enough.

"Neither their disgusting photos nor their systematic campaigns will stop the president's advance," Information Minister Ernesto Villegas said at a news conference in Caracas.

"Would El Pais publish a similar photo of a European leader? Of its director?"