MANILA (Reuters) - 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.

In the southern Philippine city of Davao, a spirited mayoral election campaign is in full swing, with candidates and their supporters out canvassing for votes.

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.