A veteran human rights activist has described the appointment of Dr Mahathir Mohamad as chairperson of Pakatan Harapan, or in the former premier's own words – "top dog" of the coalition – as the biggest betrayal of the reformasi movement.

Kua Kia Soong said it was bad enough when Harapan made an alliance with the “unrepentant former autocrat”.

“Well, now that Mahathir has been made the chairperson of the coalition, Harapan will have to answer for all his scandals...