The Philippine military says 57 people, including 26 soldiers, have been killed in clashes between government troops and militants on the country's volatile southern island of Jolo.

Military officials said Friday fighting broke out Thursday when rebels from the Abu Sayyaf militant group and Moro National Liberation Front fighters ambushed a group of soldiers transporting supplies.

At least 31 rebels have been killed in the fighting.

The clashes are the latest in a recent wave of violence in the southern Philippines and more troops are being deployed to respond to the surge in violence.

Troops have been massing in the south since early July when 14 marines were killed on the nearby island of Basilan. Ten of them were beheaded.

Thousands are fleeing for fear of getting caught in the cross-fire.

The military and government have blamed Abu Sayyaf and another rebel group, the Moro Islamic Liberation Front (MILF), for the killings. The MILF has been fighting for self-rule on Basilan for nearly three decades. In 2003, the government signed a truce with the group, but clashes continue.

The United States considers Abu Sayyaf a terrorist group with ties to the radical Jemaah Islamiyah organization. Philippine forces have been on the offensive against Abu Sayyaf since 2005, fighting primarily on Jolo.

Moro National Liberation Front fighters signed a truce with the government in 1996, but relations remain tense.

Some information for this report was provided by AFP, AP and Reuters.