Security has been stepped up across the southern Philippines, a day after six people were killed in a bomb explosion on the restive island of Mindanao.
People in Makilala were celebrating when the bomb went off
Another bomb exploded on Wednesday, causing no injuries, and a second was defused by police.
In recent weeks, intelligence experts have been warning about possible attacks by militants angry at Manila's support for the US-led "war on terror".
The US, UK and Australia have issued warnings against travel to Mindanao.
The explosion late on Tuesday targeted a stall selling alcohol in the town of Makilala.
Six people were killed and at least 29 were wounded in the blast, which happened while local people were holding a celebration for the town's 52nd anniversary.
North Catabato provincial police chief Federico Dulay said the Makilala blast was caused by a homemade bomb, fashioned from a mortar round, which exploded at about 2000 (1200 GMT).
Link to militant groups
The authorities said the device bore the hallmarks of the South East Asian militant group Jemaah Islamiah (JI).
They have also suggested that the Abu Sayyaf group could have been behind the attack.
Abu Sayyaf is the smallest and most violent militant group in the Philippines. The US has listed it as a terrorist organisation and says it has links to al-Qaeda.
Security officials said the explosions could have been prompted by the arrest last week of Istiada Binti Oemar Sovie, the wife of Dulmatin, one of the region's most wanted terror suspects.
Dulmatin is believed to be a senior member of JI, and has been accused of planning and executing the Bali attacks in 2001 that killed 202 people. He has a $10m bounty on his head.
He is believed to be hiding on the southern Philippine island of Jolo, helping to train Abu Sayyaf guerrillas.
"We suspect that the explosion were made by groups sympathetic to Dulmatin," national police chief Oscar Calderon told local media.