Dr Mahathir will helm the Home Ministry while Muhyiddin recovers from surgery.
Anwar undergoes surgery in Turkey, with the next operating scheduled for Thursday.
Six more canned sardine brands from China contaminated with worms have been pulled from the market.
Worms causing anisakiasis disease were found in canned sardines from China.
No visitors are allowed for Anwar who has been admitted to hospital for a severe prolapsed disc.
Politicians are interfering in the actions taken against dirty eateries.
Famous banana leaf restaurant among three PJ eateries ordered to close.
A video hs gone viral of Raj's Banana Leaf's dishes being washed in murky water in the back lane of the restaurant.
Two brands of China canned sardines have been found to contain dead worms.
WHO says Australia exported listeria-tainted melons to nine countries, including Malaysia.
A Russian woman has died in excruciating agony after she was "embalmed alive".