MANILA — As the Philippine military attacked a rebel camp in the south on Saturday, a Swiss bird-watcher being held by the rebels used the distraction to assault one of his captors and escape, a military spokesman said.

The Swiss national, Lorenzo Vinciguerra, had been held for more than two years by the Abu Sayyaf rebel group, which the United States had labeled a terrorist organization.

The Philippine military, which has launched an offensive against the rebels to rescue captives, was conducting a ground assault and using artillery to bomb the camp when Mr. Vinciguerra seized his captor’s weapon, according to the military.

“He wrestled with his captor to get possession of a bladed weapon,” said Restituto Padilla, a military spokesman. A rebel commander, Juhurim Hussein, was believed to have been killed as the two wrestled for the weapon, Mr. Padilla said.