Former Philippine President Rodrigo Duterte was almost certain to be elected mayor of his home city by a landslide on Monday, unimpeded by his detention at the International Criminal Court on charges of murder as a crime against humanity.

The former president's win was expected, but other races in the midterms proved less predictable.

Former Philippine president Rodrigo Duterte, detained at the International Criminal Court for alleged crimes against humanity, regained the mayorship of family stronghold Davao city in a landslide vote, an initial tally showed.