BBC News presenter George Alagiah is undergoing treatment for bowel cancer, the corporation said today.
A statement said:
George Alagiah has recently been diagnosed with bowel cancer and will be off air for a while, as he undergoes treatment.
He is grateful for all the good wishes he has received thus far and is optimistic for a positive outcome.
George asks that he and his family are given the space and privacy they require whilst he recovers.
Our thoughts are with him and his family and we send them our very best wishes during this time.
Until such time as George is well enough to return to work the BBC News At Six and GMT on BBC World News will be presented as usual by familiar faces from BBC News.
Alagiah, 58, joined the BBC in 1989 as a foreign correspondent, covering the Rwandan genocide as well as several wars.
In his time at the corporation he has interviewed figures such as Nelson Mandela, Kofi Annan and Robert Mugabe.
He has presented the BBC News at Six since 2003, taking over as solo host in 2007.
The father-of-two was born in Colombo, Sri Lanka and schooled in Ghana before moving to Portsmouth and then Durham University.
In 2008 he was appointed as an OBE, while he has also won numerous awards for journalism throughout his career.