Saudi Arabia's King Abdullah has died age 90, leaving Queen Elizabeth world's oldest Monarch.

Daily mail: Saudi Arabia's King Abdullah bin Abdulaziz - the powerful U.S. ally who sought to modernise the ultraconservative Muslim kingdom with incremental but significant reforms - has died aged 90, it has been confirmed.

The royal had been in the hospital since December, battling pneumonia.

King Abdullah's half-brother Salman, 79, has become king, a statement attributed to Salman said.

His death was confirmed on state television early Thursday morning, Saudi time, with channels cutting to Koranic verses - an action often signifying the death of a top royal.

Abdullah will be buried Thursday following Muslim tradition that a burial should take place within 24 hours of death.

QUEEN ELIZABETH II BECOMES WORLD'S OLDEST MONARCH 

Queen Elizabeth II pictured with Prince Philip and the late King Abdullah

The death of King Abdullah at the age of 90 makes Queen Elizabeth II the oldest monarch in the world.

The Queen was born on April 21, 1926 and is 88 years old. 

She became Queen at the age of 25, and has reigned through more than five decades, celebrating her diamond jubilee in 2013.