* To abdicate on July 21, Belgium's national holiday
* Albert II's son Philippe will succeed him
* King, 79, says is too old (Updates with announcement)
Belgium's King Albert II said on Wednesday he would abdicate and leave the throne to his son on July 21, saying he felt too old to carry out his duties properly.
"I realise that my age and my health are no longer allowing me to carry out my duties as I would like to," the 79-year-old monarch said in a televised address.
Belgium's 53-year-old heir apparent, Philippe, who studied at Trinity College, Oxford, and Stanford University, has already led Belgian trade delegations to countries such as the United States, China and Thailand. He has four children.
The abdication comes only six months after Queen Beatrix of the neighbouring Netherlands announced she would vacate the Dutch throne in favour of her son Willem Alexander.
While the Belgian monarch has no executive powers and plays a largely ceremonial role, he is a rare uniting factor in an otherwise divided country which in recent years has seen more and more powers devolved to regional governments.
Albert II, who has three children, ascended to the throne in 1993 when his childless brother Baudouin died.
In 1999 Belgian media reported that Albert had fathered a fourth child, a daughter, in an extramarital affair in the 1960s. The palace never acknowledged this.