BEIJING - Hurdler Liu Xiang will be absent again from the annual session of China's top political advisory body this year, arousing dissatisfaction among the online population.

Staff with the first session of the 12th National Committee of the Chinese People's Political Consultative Conference (CPPCC) have confirmed that Liu, who has been a CPPCC member for six years, had asked for leave.

Meanwhile, staff with the Shanghai Track and Field Sports Management Center told reporters that Liu is receiving rehabilitation treatment in the United States and he is not able to attend the CPPCC session this year.

The political session will open on Sunday, and a new chairman of the CPPCC National Committee will be elected.

Liu's absence has triggered discontent among sarcastic web users, who are still disappointed at the athlete's unexpected withdrawal from the Beijing Olympics and his discouraging performance at the London Olympics. In addition, Liu has asked for leave -- due to sporting commitments or injury treatment -- in five annual CPPCC sessions over the past six years. He attended the political session from the beginning to the end only in 2011.

"I don't understand why he was elected CPPCC member since he is always so busy," web user "I love eating seafood" posted on Sina Weibo, China's largest Twitter-like microblogging service. "He should respect this political role."

"His withdrawal has become a habit," "ai mo da yu xin si" posted.

Liu captured the world's attention at the Athens Olympics in 2004 after winning the gold medal in the men's 110m hurdles race.

But a stubborn Achilles tendon injury hampered him in defending his title in Beijing 2008 -- and again in London last year. He suffered a first-round exit after crashing into the first hurdle in his path at the London Games, falling to the ground and breaking his Achilles tendon.

But former NBA star Yao Ming, who was first elected CPPCC member this year, appealed for more tolerance and voiced his support for Liu.

"Please don't push him too hard," Yao told reporters prior to the annual political session.