Former South Africa captain Joost van der Westhuizen is in a critical condition in hospital as he continues to fight Motor Neurone Disease.

The 45-year-old World Cup winner has been battling the illness since 2011.

A statement posted on the J9 Foundation website said he was taken to hospital on Saturday. The organisation was set up by Van der Westhuizen to aid people suffering from MND.

"The family and friends of Joost ask that you all pray for Joost," the statement read.

"He was taken to hospital earlier today and is in a critical condition.

"We ask that you all please respect the family's time at the moment.

"When we have updates, we will let you know. For now, we ask that we all bow our heads in prayer."

Van der Westhuizen is regarded as one of the finest scrum-halves in rugby history. He won 89 caps for the Springboks between 1993 and 2003, and scored 38 tries.