MANILA - Former Philippine President Rodrigo Duterte has again won the mayorship of Davao City in this year's mid-term elections, according to preliminary results released on Monday evening.

With more than 60 percent of the votes counted, Duterte had established a commanding lead, securing 405,000 votes compared to 49,000 for his closest rival, according to figures from the Commission on Elections reported by local media.

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The former president was arrested last March at Manila's international airport and was then taken to the International Criminal Court in The Hague, the Netherlands, where he is still being detained.

Under Philippine election law, only a criminal conviction in a local court can keep a candidate off the ballot.