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.

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

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

The 26-year-old Spaniard has not played since June when he suffered a shock defeat in the second round of Wimbledon by Czech Lukas Rosol.

The tournament in Abu Dhabi, which he won twice in 2010 and 2011, was to be his return to action after missing the Olympics, the US Open and the Davis Cup final, which Spain lost to the Czech Republic.

"I am very disappointed that I will not be able to compete this year in Abu Dhabi," world number four Nadal said in a statement.

"I was really excited about returning to play and I always have a wonderful experience at the event and this is the first time I will miss the tournament.

"My rehab has gone well, my knee feels good and I was looking forward to competing. Unfortunately doctors have informed me that my body needs to rest in order to fight this stomach virus. I would like to say sorry to all my fans in the United Arab Emirates and around the world, but I hope to play and win in Abu Dhabi again next year."

After the tournament in Abu Dhabi, 11-times grand slam winner Nadal was scheduled to continue his comeback in his first ATP event since the injury, the Qatar Open, starting on New Year's Eve.

The first grand slam of the season, the Australian Open, is due to begin in Melbourne on January 14.

Despite Nadal's withdrawal, the tournament can still boast world number one and defending champion Novac Djokovic as well as four other players in the top 10 - Andy Murray, David Ferrer, Janko Tipsarevic and Tomas Berdych.-Reuters