Top prosecutor stood aside after allegedly coaching son's girlfriend on how to avoid blood alcohol test

Prosecutor Margaret Cunneen has been accused of perverting the course of justice after allegedly advising her son's girlfriend on how to avoid a blood alcohol test.

The high-ranking prosecutor will be the focus of an ICAC inquiry next month, and has been stood aside from her duties until a finding is delivered.

The deputy senior crown prosecutor, along with her son Stephen Wyllie, are being investigated after allegedly advising his girlfriend Sophia Tilley to pretend to have chest pains to avoid having a blood alcohol test following a car crash.

Ms Tilley allegedly took the advice.

Ms Cunneen said in a statement:  "I deny the allegations, which can only be the result of a malicious complaint.”

NSW Attorney-General Brad Hazzard said the DPP had spoken to Ms Cunneen and she had agreed to "stand aside and have no active involvement" in any current or future prosecution until the ICAC matter has been resolved.

"It is important to recognise that any individual appearing before ICAC has the presumption of innocence and Ms Cunneen, as with any other NSW citizen, has an absolute entitlement in that regard," he said in a statement.

The three-day Independent Commission Against Corruption inquiry begins on November 10.

Due to Ms Cunneen's standing, someone will be brought in from outside NSW to preside over the inquiry.

The high-profile prosecutor has spearheaded the Skaf gang rape case and the trial of the 'butcher of Bega'.