Security forces in the Philippines suspect militants linked to the al-Qaida terrorist network may be responsible for a bombing that killed at least six people on the southern island of Mindanao.
Authorities say Tuesday's attack in Makilala, in North Cotabato province, could have been retaliation for the arrest of the wife of a Jemaah Islamiyah member wanted in connection with the 2002 bombings in Bali, Indonesia.
The wife of militant Dulmatin was arrested last week during a raid on the local militant group Abu Sayyaf. Officials believe Abu Sayyaf is sheltering Dulmatin and another Indonesian terrorism suspect Umar Patek.
Another bomb exploded Wednesday in the southern city of Cotabato, but caused no injuries.
The United States and Australia have issued travel warnings to their citizens in Mindanao, noting concerns about more attacks.
Tuesday's bomb, a mortar shell attached to a cellphone triggering mechanism, exploded during a civic celebration in Makilala. Another bomb exploded earlier at a public market in southern Tacurong city, wounding at least four people.
The Philippines has been fighting insurgencies waged by Islamist and communist guerrillas in its southern provinces.
Some information for this report was provided by AFP and AP.