Crown Prince Philippe was sworn in as king of Belgium Sunday following the emotional abdication of his father Albert II.

Phillippe, 53, took the oath as the country's seventh king in a ceremony in parliament.

Belgium has a constitutional monarchy in which the king plays a largely ceremonial role, but he has been called upon to resolve recurring constitutional crises caused by the deep divisions between the Dutch-speaking north and the French south.

Albert’s resignation on grounds of ill health came after nearly 20 years on the throne and was timed to coincide with Belgium's national day.

In a ceremony topped off by trumpet fanfare and cannon-fire, Philippe took his oath in the country's three official languages -- Dutch, French and German.

Flag-waving supporters gathered in the midday sun waiting for their new king and his wife, Mathilde, to greet them from the balcony of the nearby royal palace.

But not everyone was celebrating.

The far-right separatist Vlaams Belang (Flemish Interest) party boycotted the ceremony, the BBC reported, and Jan Jambon, parliamentary head of the N-VA (New Flemish Alliance) that wants Flanders to break away and favors a republic, said the occasion "leaves me cold." His party leader Bart De Wever also skipped the ceremony.

King Albert thanked an audience of some 250 dignitaries and political leaders "for all that you have achieved during my reign." He then embraced his son and signed the official abdication papers, ending his reign.

King Albert exercised his authority in mediating between political leaders on the formation of a government during the 2010-2011 parliamentary stalemate, when Belgium was left without a government for 541 days after elections failed to find a clear winner.

President Barack Obama sent the new king congratulations, said American National Security Council spokeswoman Caitlin Hayden. "The president also sends his heartfelt appreciation to King Albert II for his warmth, service, and leadership as he steps down after nearly 20 years," the statement said. "Belgium is a valued friend of the United States, and the president looks forward to continuing to deepen this bond in the years to come."

Albert announced his abdication plans less than three weeks ago, so there was little time to turn the occasion into a huge international event. No foreign royals were at the ceremony, the AP reported. Since the royal transition coincides with Belgium's national day celebrations, a military parade had already been planned.

Philippe has been groomed for the job as a leader of foreign trade delegations over the past two decades. "He is a very wise person, a person who is very well prepared," said EU Commission President Jose Manuel Barroso, who attended the ceremony. "He knows the politics of Belgium and Europe very well."