The Philippines has recalled its ambassador to Canada, Manila's foreign minister said Thursday, in an escalation of a festering diplomatic row over tonnes of trash shipped to the Southeast Asian nation.

Filipinos headed to the polls on Monday in a vote that is expected to strengthen President Rodrigo Duterte's grip on power, opening the way for him to deliver on pledges to restore the death penalty and rewrite the constitution.

More than 18,000 positions are at stake, including half of the seats in the upper house Senate, which has served as a bulwark against some of Duterte's most controversial policies.

Hundreds of barefoot men beat themselves with flails and at least 10 were to be nailed onto crosses throughout Good Friday in a blood-soaked display of religious fervour in the Philippines.

A bomb blast outside a restaurant on Wednesday wounded at least 13 people, including children, in the insurgency-plagued southern Philippines, authorities said.

The explosion shattered a window at the front of the eatery, striking family members gathered for an event in the town of Isulan on Mindanao island, Mayor Marites Pallasigue told AFP.

The European Union said Saturday it would investigate allegations that its aid funds were being funnelled to Philippine communist guerrillas waging a decades-old insurgency that has killed thousands.

The Philippine government demanded the probe, alleging that aid supplied to a local non-profit by the EU was being diverted to the Communist Party of the Philippines and its New People's Army (NPA), the bloc's office in Manila said.

The Philippines was poised to officially quit the International Criminal Court on Sunday, though the beleaguered tribunal has pledged to pursue its examination of possible crimes in the government's deadly drug war.

Thousands of women took to the streets of Manila Friday in protest against President Rodrigo Duterte's alleged misogyny as an exhibition marking International Women's Day exhibited the clothes of Philippine rape victims.

Protesters marched on Malacanang presidential palace chanting against Duterte, who has repeatedly made jokes about rape and said last year that when he was a teenager he indecently "touched" the family maid.

At least 18 people were killed Sunday when two bombs hit a Catholic church on a southern Philippine island that is a stronghold of Islamist militants, the military said, days after voters backed Muslim self-rule in the region.

The Philippine Congress granted President Rodrigo Duterte's request to extend martial law in the country's south until the end of 2019 on Wednesday, ignoring opposition warnings of a creep towards authoritarian rule.

President Rodrigo Duterte on Friday asked legislators to extend martial law across the southern Philippines until the end of 2019 in order to quell continuing violence in the restive region, officials said.

Duterte's request, which could be approved as early as next week, comes despite critics voicing concerns the move threatens human rights and places too much power in the leader's hands.