Dr Mahathir’s accusations of ruling party leaders accepting bribes “warrant police action”, a spokesperson said.
Dr Mahathir and the Bersih pro-democracy movement have called for current PM Najib Razak to resign over corruption allegations.
Tens of thousands attended Bersih’s weekend rallies across the country.
A spokesman for Dr Mahathir, Sufi Yusoff, told Reuters: “As far as I am aware he has not been approached by the police yet. We will comply with the police on whatever is needed.”
It was unclear whether Dr Mahathir could face charges.