ISIS in the Sinai Peninsula released a video Wednesday in which they threaten to execute a Croatian national if the Egyptian government refuses to hand over captured female fighters.

The video shows an ISIS fighter in combat gear and with his face covered, standing in front of a man kneeling. Identified as 30-year-old Tomislav Salopek, the man said he worked for the French company CGG, a Geoscience company. Salopek explained he worked at the company’s Cairo branch was kidnapped on July 22.

In exchange for Salopek’s release, the masked fighter demanded female ISIS fighters being held captive should be released. If they are not released within 48 hours, the knife-wielding fighter threatened to execute Salopek.

The SITE Intelligence Group, a watchdog of Islamic extremist online activity, first reported on the video and posted still images showing Salopek and the ISIS fighter.

ISIS forces in the Sinai Peninsula have grown in notoriety in the recent weeks, having attacked Egyptian security and military forces. The group gained global notice after it attacked Egyptian navy vessels on the Mediterranean coast back in July 16, reported CBS News and the AP. The group claimed responsibility for the attack.

ISIS’ influence in the region has grown so much Israel has openly expressed the possibility of attacking the Islamic extremists in the peninsula, reports the AFP.

Neither the Croatian nor Egyptian governments have made statements concerning the video.