The ruling body for women's tennis is investigating whether Venus Williams genuinely had an injury preventing her from playing in this week's WTA Championships in Munich.

"Under our rules, if a player withdraws from the championships after she has qualified, we set up an independent committee of three people to look into whether she was unable to play by reason of physical incapacity," outgoing WTA tour chief executive officer Bart McGuire said yesterday.

The Wimbledon and US Open champion irritated tour officials by pulling out of the year-end event on Friday, saying she had a sore wrist.

Williams had repeatedly assured the WTA that she would play in the Munich tournament for the world's top 16 players, which started yesterday. Her late withdrawal could cost her $140,000 in year-end bonus money.

World number two Lindsay Davenport on Monday criticised Williams for the withdrawal.

"It would have been better if she'd pulled out earlier," she said. "I think it was wrong because she left it so late after saying many times that she would be coming."

McGuire, who leaves his post at the end of the year, said: "We have set up a panel that includes two medical doctors and a lawyer who has been involved in a great number of prominent high-visibility arbitrations in the United States."

He added that doctors would be appointed yesterday and that he would make no further comment until the result of the investigation.