An unannounced trip by former Philippine President Rodrigo Duterte to Hong Kong has set off speculations that he may be trying to evade a possible arrest warrant by the International Criminal Court over his bloody crackdown on drugs.

Former Philippines President Rodrigo Duterte said in Hong Kong that he was ready for possible arrest amid reports the International Criminal Court (ICC) was poised to issue a warrant over his years-long "war on drugs" that killed thousands.

Duterte again came under the spotlight during a weekend trip to Hong Kong when the trip sparked speculation that he may have gone into exile to evade arrest. He had appeared as the main speaker on Sunday at a gathering of thousands of cheering and flag-waving Filipino expatriates, who jammed Southorn Stadium in downtown Wan Chai district.