Philippine forces have killed three suspected sympathizers of the Islamic State group but failed to capture their leader in a clash in the country's south, an army official said Sunday.

Troops seized two rifles and an IS-style black flag of the slain militants, who belonged to a small armed group called the Ansar Al Khilafah Philippines, following Saturday's clash near Maasim town in Sarangani province, said army Maj. Gen. Rafael Valencia.

A militant was captured by the troops prior to the fighting near Maasim, Valencia said.

Military officials said the militants, led by their leader, Mohammad Jaafar Sabiwang Maguid, were spotted in a hinterland by villagers, who notified the troops.

Valencia said Maguid and several of his men, possibly including some foreigners, managed to escape before the clash, adding that the militants aspire to be affiliated with the Islamic State group.

A number of other Islamic groups in the southern Philippines, including Abu Sayyaf, have pledged allegiance to IS, but the military says there has been no sign of a direct collaboration between Filipino gunmen and the militants in Syria and Iraq.