Controversial Philippine president Rodrigo Duterte has announced his surprise resignation, fuelling speculation he is clearing the way for his daughter to run to succeed him.

More than 60 million Filipinos will vote in May for a new president, vice president and more than 18,000 politicians and local government officials.

Mr Duterte came to power in 2016 and gained support in the Philippines, but was criticised abroad, for his heavy crackdown on drugs which resulted in thousands of suspects being killed.

His retirement follows Filipino boxing legend Manny Pacquiao announcing his own plans to run for president and accusing Mr Duterte of corruption.

Mr Duterte had earlier announced plans to run for vice-president but has backed out.

Philippine President Rodrigo Duterte and his daughter Sara Duterte. Photo: Getty

“Today, I announce my retirement from politics,” he said, accompanying loyalist Senator Christopher ‘Bong’ Go from their ruling PDP-Laban party as Mr Go registered to run for vice president.

Mr Duterte, 76, had been expected to run for the No.2 position himself, a plan which most Filipinos oppose as violating the spirit of the constitution, which sets a one-term limit for the president to stop power from being abused.

“In obedience to the will of the people, who after all placed me in the presidency many years ago, I now say to my countrymen, I will follow your wish,” said Mr Duterte as he urged the public to support the candidacy of his longtime aide.

Boxing champion Manny Pacquiao plans to run for president of the Philippines next year.

Political observers had long suspected Mr Duterte could spring a surprise, such as a presidential run by his daughter, Sara Duterte-Carpio, next year.

Ms Duterte-Carpio, who in 2016 replaced her father as mayor of Davao, said last month she was not campaigning for higher office, after agreeing with her father only one of them would run for national office in 2022.

The older Duterte’s decision not to join the race next year would clear her way.

“This allows Sara Duterte to run,” said Antonio La Vina, professor of law and politics at the Ateneo de Manila University.

But La Vina added he could not rule out the possibility the firebrand leader could have a change of heart and be Go’s substitute.

Candidates have until Friday to register, but withdrawals and substitutions are allowed until November 15, leaving scope for last-minute changes of heart, like the 11th-hour entry of Duterte for the 2016 election, which he won by a huge margin.

Political analyst Earl Parreno said he suspected the Dutertes were using the same playbook and that Duterte-Carpio would join the race at the last minute.

She did not immediately respond to a request for comment.

-with AAP