A series of explosions rocked Sunday night a southern Philippine city known for Islamic State-linked violence, wounding at least 17 people including soldiers, a military official said.

A hand grenade was thrown into a military truck patrolling Cotabato City in the restive southern island of Mindanao, with 8 soldiers and 4 civilians sustaining injuries from the bomb's shrapnel.

It was quickly followed by an improvised explosive device (IED) blast in the nearby town of Libungan, wounding five civilians with one in "serious" condition, regional military spokesperson Major Arvin Encinas said.

Another explosion was recorded in the neighboring town in Maguindanao, although police are still gathering information on whether there are casualties.

No groups have yet claimed responsibility for the attacks, which happened as the government planned this year to lift its military rule in the island over the improving security situation.

"We do not discount the possibility that Bangsamoro Islamic Freedom Fighters (BIFF) and Daesh-inspired groups are behind this," Encinas told AFP, referring to the Islamic State-linked militants.

The Philippines is plagued by violent insurgencies, including a Muslim-led separatist uprising in Mindanao that has killed some 100,000 people.

Though a landmark peace deal with the largest of the rebel groups, the Moro Islamic Liberation Front, was sealed in 2019, the most brutal extremist factions were not included.

Those groups include the Islamic State-aligned BIFF and Abu Sayyaf, a kidnap-for-ransom gang that has been behind some of the nation's deadliest attacks.

Two people were killed and 35 wounded in Cotabato in December last year after a bomb went off outside a shopping mall, which was also blamed on Islamic State-linked militants.

A worrying escalation of militancy was recorded in June when a Filipino jihadist -- who military named as the first local suicide bomber -- blew himself up in an attack on a military base.

Islamic State has stepped up its strategy of absorbing existing insurgent groups around the world as its "caliphate" crumbled in the Middle East.

In May 2017, hundreds of pro-IS gunmen seized the Muslim city of Marawi, sparking a five-month battle that left more than 1,000 people dead.