Malaysia's former prime minister Mahathir Mohamad has denied engaging in corruption, saying he earned his money from his salary during his decades-long political career and most of it is "now gone".

In an interview with Al Jazeera, Mahathir, who is under investigation by the country's anticorruption agency, hit out at current Prime Minister Anwar Ibrahim over remarks that implied that he had used his time in office to enrich himself and his family.

Mahathir also accused Anwar of targeting his two eldest sons, Mirzan Mahathir and Mokhzani Mahathir.

The Malaysian Anti-Corruption Commission (MACC) in January ordered Mirzan Mahathir to declare all his assets in and outside the country as part of an investigation following revelations contained in the so-called Panama Papers, reports AFP.