A Muslim extremist rebel leader has threatened to behead an American couple before the Philippine president’s visit to the United States next month, if the army does not halt its offensive on the group.

Deadly street battles erupted in a southern Philippines town today as a self-styled ‘‘suicide squad’’ of Muslim extremists invaded a hospital and church, seizing patients, doctors and a priest.

A Muslim extremist group that snatched 20 people, including three Americans, from an island resort in the Philippines threatened today to kill all the hostages if the military moves attempt to rescue them.