FACTBOX: Thai king skips speech due to throat infection

(Reuters) - Thailand's revered King Bhumibol Adulyadej has a throat infection and is on a drip, his daughter said on Thursday after he failed to make his traditional birthday eve address amid a crippling political crisis.

Bespectacled and quietly spoken, the world's longest reigning monarch, who turns 81 on Friday, is seen as semi-divine by many of Thailand's 65 million people.

Following are some facts about the king, whose name means "Strength of the Land, Incomparable Power."

* Born on December 5, 1927 in Cambridge, Massachusetts, the third and youngest child of Prince and Princess Mahidol of Songkhla.

* Ascended to the throne on June 9, 1946, the day his elder brother, King Ananda Mahidol, died in a mysterious shooting. He switched his studies in Lausanne, Switzerland from science to political science and law.

* Married to the daughter of a prince on April 28, 1950, who became Queen Sirikit. They have four children:

- Princess Ubol Ratana, born on April 5, 1951 in Lausanne.

- Crown Prince Maha Vajiralongkorn, born on July 28, 1952 in Bangkok

- Crown Princess Maha Chakri Sirindhorn, born on April 2, 1955, in Bangkok

- Princess Chulabhorn, born on July 4, 1957, in Bangkok.

* Though a constitutional monarch seen as above politics, the king's influence is considerable and he has intervened thrice in the past to end bloodshed or break deadlocks.

- In October 1973, he intervened at the height of bloody student demonstrations against a military government and persuaded the generals to step down and leave the country.

- In May 1992, he intervened after three days of bloody street clashes between troops and pro-democracy demonstrators which left scores dead and hundreds wounded.

- In April 2006, he summoned top judges to his seaside palace and told them to resolve a political crisis after an inconclusive April 2 general election left the country with a caretaker government and no functioning legislature.

* The king has been treated for a range of ailments in recent years, the latest in 2007 when he spent three weeks in hospital receiving treatment for a blood clot in his brain.

He had an operation on a restricted spinal canal in July 2006, shortly after huge celebrations of his 60 years on the throne.