The move comes after investigators said his family had failed to account for the source of its financial assets.
The probe began when the Panama Papers leaks linked his children to offshore companies used to buy London flats.
This fuelled suspicion the companies were used to launder ill-gotten wealth, claims Mr Sharif strenuously denies.
He says the properties in London were acquired legitimately and that he personally does not own them.
But the issue is turning into a major challenge to him. Opposition groups accuse his family of using their political influence to amass wealth by unlawful means and are calling on him to resign.