Prime Minister Dr Mahathir Mohamad has taken temporary charge of the Home Ministry as minister Muhyiddin Yassin goes on medical leave.
Muhyiddin had undergone surgery to remove a growth on his pancreas and is expected to resume his duties next month.
"(The growth) was detected in the early stages. Thank God, the surgery was successful and he is in stable condition," Muhyiddin's press secretary Hafiz Abdul Halim said in a statement.
Hafiz said that the minister will thus miss the MPs oath-swearing ceremony in Parliament next week.
Mahathir at present does not have a portfolio because the Pakatan Harapan manifesto bars the prime minister from holding other portfolios.
Mahathir last helmed the Home Ministry during his first tenure as prime minister.
He served the ministry from 1986 until 1999.