Attempts from within Umno to defend prime minister Najib Abdul Razak over allegations linked to state-investor 1MDB has now reached a ludicrous level, said former premier Dr Mahathir Mohamad.

Speaking at a press conference today, Mahathir referred to the reported statement by Langkawi MP Nawawi Mohamad, allegedly linking Yang di-Pertuan Agong Abdul Halim Mu'adzam Shah to the 1MDB scandal.

"Now there is there the allegations by the United States Department of Justice that funds from 1MDB was siphoned by Najib's stepson Riza Aziz, his friend Jho Low and an individual identified as Malaysian Official 1.