Prime Minister Najib Abdul Razak had been accused of derailing the investigations of a special task force concerning 1MDB and the RM2.6 billion in his private bank accounts when Abdul Gani Patail was suddenly removed as attorney-general.

The official reason for the change was health reasons, but this failed to convince former premier Dr Mahathir Mohamad.

"The AG (Gani) was said to be sick, but he denied he was sick.

"As far as is known, no medical certificate certifying that he was sick seems to have been issued," he said in a blog posting today.

Mahathir also accused Najib of "usurping the powers of the judiciary" when he removed Gani while he was preparing the case for the courts and appointed a judge Mohamed Apandi Ali to take over the post.

Ironically, the former premier himself had been accused of castrating the judiciary during his tenure, which included the sacking of then lord president Salleh Abbas.

Same treatment

Mahathir also alleged that Najib, as head of the elected legislators, failed to respect the principle of separation of powers.

For example, he said officers of the administration who were investigating 1MDB and the RM2.6 billion were transferred out to the Prime Minister's Department, resulting in them stopping their work.

"Their replacements apparently were with the approval of the prime minister.

"Officers of the MACC have been similarly treated, again resulting in the investigations being obstructed," he added.

Mahathir has repeatedly called on Najib to step down and even accused his once blue-eyed boy of committing theft.

However, the prime minister has denied any wrongdoing and claimed that Mahathir was part of a conspiracy, which included the foreign media, to topple him.

As for the RM2.6 billion, the sum has been described as a political donation from a Middle Eastern source.