Spanish King Juan Carlos announced Monday he will hand the crown to his son Felipe, ending a historic 39-year reign that guided Spain to democracy but was weakened by scandals.

The 76-year-old, crowned in November 1975 after the death of General Francisco Franco, said he wanted to hand over to "a younger generation" after several turbulent years.

Juan Carlos was widely respected for his role in building modern Spain, but a corruption scandal that struck his family at the height of an economic crisis undermined his popularity.

Years of economic crisis "have awakened in us a desire for renewal, to overcome and correct mistakes and open the way to a decidedly better future", the king said in a televised address.

"Today a younger generation deserves to step into the front line, with new energies," said the monarch, looking relaxed in a grey suit and green tie.

"For all these reasons... I have decided to end my reign and abdicate the crown of Spain."

King Felipe VI

Spain's new king will be his son Felipe de Borbon, Prince of Asturias, a six foot six inch- (1.98 metre-) tall former Olympic yachtsman, relatively unscathed by the family's scandals.

The future King Felipe VI "has the maturity, the readiness and the sense of responsibility needed to take on the leadership of the state and open a new phase of hope," Juan Carlos said.

Experts warned Felipe has a tough job ahead to unite a country suffering from a recession that ended last year, with an unemployment rate still close to 26 percent.

A corruption scandal implicating the king's youngest daughter Cristina and her husband Inaki Urdangarin has plunged the palace into a crisis of its own.

"It is a very difficult moment to come to the throne," said Jose Apezarana, author of several books on the royals.

"We have a country that is in an economic crisis and the Urdangarin case has not yet been resolved," he told AFP.

"The Urdangarin case is from now on going to wear down Felipe, not Juan Carlos."

An act of parliament is needed to bring the abdication into force. Prime Minister Mariano Rajoy called a cabinet meeting for Tuesday to draw up the required legislation. The prime minister said he hoped Felipe would be proclaimed king "very soon".

Ex-newsreader queen

The prospect of the king's son Prince Felipe, 46, taking over seemed like a fresh start to passers-by on the streets of Madrid on Monday.

"It was something that clearly had to happen," said Maria Jose Gonzalez, 55. "The king is elderly. Felipe is very prepared and will do very well."

Felipe's succession also means Spain will have its first "commoner" queen: Felipe's wife Princess Letizia, a former newsreader.

In a poll by Sigma Dos in January 2014, the number of people with a high opinion of the king fell nine percentage points over 2013 to 41 percent.

Those wanting him to abdicate in favour of Felipe surged by 17 percentage points to 62 percent.

Some would prefer no king at all, however, and Twitter buzzed with irreverent messages about Juan Carlos and calls for a referendum on the monarchy.

"I would like for us Spanish people to be able to choose whether we want a monarchy or a republic. The monarchy is obsolete," Alejandro Ricas, a 19-year-old student, told AFP.

Coup-stopper

Juan Carlos shaped Spain's modern history after taking the throne as the dictator Franco's appointed successor.

Defying Franco's supporters, he oversaw the creation of a parliamentary monarchy, with a new constitution approved by referendum in 1978.

He was credited with seeing off an attempted coup in February 1981 when soldiers stormed into parliament shooting and held lawmakers hostage.

Juan Carlos said on Monday he had worked to make "citizens the masters of their own destiny and our nation a modern democracy".

"When I look back, I can only feel pride and gratitude towards you," he told the nation.

"Pride for the many good things we have achieved together over the years, and gratitude for the support you have given me."

Graft probes, sore hips

But he was undermined late in his reign by the scandal centring on Urdangarin's business affairs, which broke out in 2011 and has also dragged in Cristina.

Juan Carlos further angered Spaniards by going on a luxury elephant-hunting safari to Botswana in April 2012 as his subjects struggled in the recession.

His ailing health also raised questions about his future. Between May 2010 and November 2013, he had surgery nine times, including five hip operations.

Juan Carlos was the third European monarch of his generation to abdicate in just over a year, after King Albert II of Belgium in July and Queen Beatrix of the Netherlands in April, 2013.

Among tributes to the Spanish king, German chancellor Angela Merkel said her "numerous meetings with him were always very deep and constructive".

Spanish tennis star Rafael Nadal at the French Open called him "a wonderful person who was a great representative of our country".