Spain's King Juan Carlos has defended the monarchy's role after protests against it in the country's north-east.
Many Spaniards believe the monarchy has outlived its use
He said the parliamentary monarchy was a pillar of Spain's constitution that had given the nation its longest period of democratic stability since 1975.
It was an unusual move by the king, who is normally neutral on politics, the BBC's Pascal Harter in Barcelona says.
Catalan separatists were recently in court for burning pictures of the king, prompting a debate over the monarchy.
Speaking in the northern city of Oviedo, King Juan Carlos said the parliamentary monarchy had allowed Spain to "live its longest period of stability and prosperity in a democracy" since the death of military ruler Gen Francisco Franco in 1975.
There is enormous respect among Spaniards for the role the king played in the country's transition to democracy and for his decisive support of that democracy when it was threatened by a military coup in 1981, the BBC's Barcelona correspondent, Pascal Harter, says.
But many believe the monarchy has outlived its use, our correspondent says.
They say the king should step down from politically sensitive roles, such as head of the armed forces - a proposal made last week by one Catalan party.
The debate started after two Catalan separatists publicly burnt pictures of the king in September.
It has now extended beyond the north-eastern region of Spain and on to the pages of national papers.