In a new video released on Wednesday, the Islamic State (Isis) militants have threatened to behead a Croatian hostage, if Egyptian authorities do not release "Muslim women" held in its prisons within 48 hours.

The Isis video titled "A Message to the Egyptian Government," released on the social media, shows a man wearing a yellow jumpsuit kneeling in the desert before a knife-wielding masked man in military fatigues.

An Islamic State flag is seen in the background. The video is claimed to have been released by the Isis affiliates in Egypt's Sinai Peninsula.

Intelligence monitoring agency - SITE group said on Twitter that the Croatian hostage identified as Tomislav Salopek works in the Cairo branch of the French geoscience company CGG.

In the video, the Isis hostage reads out a note in English, and identifies himself as Tomislav Salopek, a married, 30-year-old father of two.

He then adds that the Isis fighters captured him on 22 July. And if Egyptian authorities do not act, he said, "The soldiers from Wilyat Sina will kill me." Wilyat Sina is the Arabic name of the Isis-affiliate group in Egypt.

The video demands that Egypt should release the 'Muslim women' imprisoned by the authorities. It is, however, not clear who exactly the militants wanted.

Egypt, a majority Muslim country, holds hundreds of Islamists and suspected supporters of the outlawed Muslim Brotherhood group in prisons.

Croatia last month had said that one of its nationals with the same initials had been kidnapped in Cairo while on the way to work.

The company, which Salopek identified as France's CGG Ardiseis, works in the oil and gas sector and has a branch office in Maadi suburb of Cairo.