Since launching a series of attacks against Najib Abdul Razak, Dr Mahathir Mohamad has, for the first time, roped in the prime minister's wife Rosmah Mansor.

"There are many things about his (Najib's) personal behaviour that I thought were not right.

"But I was prepared to overlook them, including his and his wife's lavish lifestyles," Mahathir said in his latest blog post.