Former premier Dr Mahatahir Mohamad's decision to drag Prime Minister Najib Abdul Razak to court is "shocking" to Minister in the Prime Minister's Department Azalina Othman.

Mahathir and two others today filed a suit against Najib for malfeasance and failure to uphold fiduciary duties.

"I am shocked but not surprised," Azalina told reporters in the Parliament lobby, adding that she would issue a press statement on this later.