The Philippines has rejected claims made by the Islamic State group, also known as ISIS, that it killed 100 soldiers in recent clashes on the island of Basilan, Reuters reported Thursday. Authorities reportedly said that the ISIS claims were "purely propaganda" and there was no evidence to link the Sunni-militant group to the local Abu Sayyaf.

Clashes between Philippine troops and Abu Sayyaf militants erupted after the military attacked a stronghold of the Islamic rebels on the island of Basilan. Authorities reported that 46 people were killed in battles this week, while the fighting entered its sixth day Thursday.

"With the grace of god we were able to detonate seven trucks carrying soldiers," ISIS had reportedly said, while claiming they attacked Philippine troops, Reuters reported, citing SITE Intelligence, a US-based group that tracks online activity of jihadi organizations.

Abu Sayyaf, which is known for extortion, kidnappings, beheadings and bombings, was established in the early 1990s in the country's Basilan province, about 100 miles northeast of Sulu. The Philippines government said there was no proof to link the group to ISIS.

Meanwhile, concerns over the ISIS spread in Southeast Asia have increased as nearly 1,200 people from the region have reportedly joined ISIS in the Middle East. Several experts have claimed that an ISIS stronghold in the southern Philippines could target the region.