Umno has warned against protests over the conditional pardon that allowed its former president Najib Abdul Razak to serve the remainder of his prison sentence under home detention, saying such actions could be seen as challenging the constitutional authority of the Malay rulers.

The warning by Umno president Ahmad Zahid Hamidi comes amid growing discontent over Najib's home detention, which began last night after he settled a RM50 million fine in the SRC International case.

The decision has prompted political fallout within the government, with DAP secretary-general Anthony Loke following through on his pledge to resign as transport minister in protest.

Amanah president Mohamad Sabu, meanwhile, is forgoing his salary as agriculture and food security minister to fund NGOs advocating for a fair house arrest mechanism that would benefit all convicts.