Pope Benedict XVI has urged Cuba to find a new model to replace the country's ruling Marxist ideology.
The pontiff spoke to reporters on his plane while flying from Rome on a visit to Mexico and Cuba.
Benedict said "it is evident that Marxist ideology as it was conceived no longer responds to reality."
Responding to the comment, Cuban Foreign Minister Bruno Rodriguez said the Cuban system was a "developing social project, which is constantly perfecting itself."
Cuba has been a communist state since 1961.
Benedict arrived in Mexico on March 24 at the start of a six-day trip of Latin America.
The pope landed in the city of Silao, where he was greeted on the tarmac by President Felipe Calderon and first lady Margarita Zavala.
Before his arrival, Benedict called on Mexicans to conquer an "idolatry of money" that feeds drug violence that has claimed more than 47,000 lives in the country since a government crackdown began in 2006.
Based on reporting by AP, Reuters, and AFP