Public Protector Busisiwe Mkhwebane has defended her subpoena on Minister of Public Enterprises, Pravin Gordhan, saying she was not harassing him and is conducting a legitimate investigation. 

Her office added she was disappointed the subpoena was almost immediately leaked to the media. 

Fin24 reported on Thursday evening that Mkhwebane ordered Gordhan to submit an affidavit in relation to the establishment of the so-called South African Revenue Service (Sars) 'rogue unit'. 

Gordhan's spokesperson, Adrian Lackay, told Fin24 on Thursday afternoon that the subpoena amounted to an "abuse of office" by Mkhwebane.

[The] same set of allegations have been investigated repeatedly by various institutions – including the office of the Public Protector in 2014 – and no conclusive evidence could be found of any illegality by Sars or Minister Gordhan," said Lackay.

On Friday Mkhwebane's office said the probe was legitimate. 

"[The Public Protector] has, in the past, subpoenaed and interviewed numerous Ministers, Members of Executive Councils and Premiers as part of investigations. Not once did any of these public office-bearers take issue with this, label it 'harassment' or see it as a source of irritation," she said.