Former prime minister Dr Mahathir Mohamad and four others have joined the growing number of parties seeking to intervene in a suit over the Yang di-Pertuan Agong's decision to refuse the emergency proclamation last year.

The five, including Jerlun MP Mukhriz Mahathir, Kubang Pasu MP Amiruddin Hamzah, Sri Gading MP Shahruddin Md Salleh and senator Marzuki Yahya, filed the intervener application on Jan 12.