Buthelezi readmitted 'for further treatment'

But his office says he's not critically ill.

It's confirmed he underwent a minor procedure for back pain that had been bothering him for a while and had routine tests done. 

Buthelezi's spokesperson, Liezl van der Merwe, says the IFP founder was discharged but had to be readmitted for further treatment.

"The nation will be kept abreast as and when necessary. 

"A request has been made that well-wishers please refrain from visiting, as a speedy recovery depends on rest."