DAVAO (AFP) - Philippines police on Sunday (Sept 4) were searching for three people wanted for questioning over the bombing of a night market in President Rodrigo Duterte's hometown blamed on a notorious group of Islamic militants.

The blast, which tore through a bustling market in the heart of Davao city on Friday, killed at least 14 people and led to the President imposing a "state of lawlessness" on the country.

Police are searching for two women and one man for questioning over the bombing, which has been widely been blamed on the Muslim extremist Abu Sayyaf group, said Chief Inspector Andrea de la Cerna on Sunday.

Davao is the hometown of Mr Duterte, who had recently ordered an offensive against the Abu Sayyaf.

He has said that the explosion was in retaliation for the military operation against the group in their stronghold in the southern island of Jolo.

However, Insp De la Cerna, spokesman of a task force investigating the explosion, said they were not ruling out other motives for the attack.

"We have copies of the CCTV (closed-circuit television), we have eight possible witnesses but we have named no one (as suspects)," she told AFP.

She said the three "persons of interest" being sought were not yet considered suspects, but would not give further details.

Mr Duterte believes the attack was "80 per cent" likely an act of terrorism, his spokesman Martin Andanar told reporters on Sunday.

After the bombing, Mr Duterte declared a national "state of lawlessness", which his security adviser said gave the military extra powers to conduct law enforcement operations normally done only by the police.