S Africa spinner Botha reported

Botha's action was called into question by the umpires following the third Test against Australia in Sydney.

But United Cricket Board chief Gerald Majola said they believed Botha's action was legitimate.

"He has bowled at first-class domestic level for two seasons without once being reported," said Majola.

"We hope Johan's promising career will continue to progress at a time when everybody in world cricket is trying to encourage the art of spin bowling in South Africa and elsewhere."

The UCB expects to receive a formal report on the matter either on Sunday or Monday.

Related feature: What is a doosra?

Match referee Chris Broad has confirmed that it is Botha's doosra, a ball which spins from leg to off, and quicker delivery which are under scrutiny.

"We are therefore requesting the ICC to commission a biomechanical report into the bowler's action in accordance with the process introduced last year," said Broad.

Botha can carry on playing for South Africa, and has been named in the squad for the one-day VB Series against Australia and Sri Lanka, but he could be suspended if his action is found to be illegal.

He is not the first off-spinner whose action has been called into question for bowling the doosra.

Sri Lanka's Muttiah Muralitharan and Harbhajan Singh of India have also had to undergo testing to prove the legitimacy of their actions.

Professor Bruce Elliott of the University of Western Australia believes it is very difficult for an off-spinner to stay within the guidelines, which allow bowlers to straighten their arms by up to 15 degrees.

He told BBC Sport last year: "To bowl it you really have to get your fingers over the top of the ball. The problem for most of them is to do that they have to extend the elbow.

"It's a question of controlling the elbow so it's not too flexed [bent] to start with because it's almost impossible to get the hand over the ball without extending it further."