Rafael Nadal's comeback from a long-term knee injury has been put on hold by an illness that has ruled him out of an exhibition tournament in Abu Dhabi in the United Arab Emirates.

"Rafael Nadal has been forced to make a last-minute withdrawal from the 2012 event due to a stomach virus," organizers said on Tuesday.

"Nadal, who has competed in all four previous tournaments, was advised by doctors not to travel or compete due to the illness."