In an unexpected reversal of course, Rajat Gupta, the former Goldman Sachs director accused of insider trading, will not testify in his trial according to a letter to the presiding judge.

The letter is in direct contradiction to a statement made on Friday afternoon by Gary Naftalis, Gupta's lawyer, in which he said it would be ‘highly likely' that his client would testify.

Gupta, the former worldwide head of McKinsey, is accused of revealing corporate secrets to his former business partner Raj Rajaratnam, founder of Galleon hedge fund.

Prosecutors estimate that Galleon made $13.5m and avoided $3.8m in taxes based on Gupta's alleged tips. He denies wrongdoing.

By law Gupta is not required to take the stand in his own trial. Lawyers believe that testifying can influence the jury's perception of whether the prosecution has proved the case beyond reasonable doubt or whether they believe the defendant. Recent high-profile cases, such as Bernard Ebbers, former head of WorldCom, where defendants have chosen to testify have ended in convictions.

Gupta's trial is ongoing.