FILE - This undated file image posted on a militant website on Tuesday, Jan. 14, 2014 shows fighters from the al-Qaida linked Islamic State of Iraq and the Levant (ISIL) marching in Raqqa, Syria. Once a vibrant, mixed city considered a bastion of support for President Bashar Assad, the eastern city of Raqqa is now a shell of its former life, transformed by al-Qaida militants into the nucleus of the terror group's version of an Islamic caliphate they hope one day to establish in Syria and Iraq. In rare interviews with The Associated Press, residents and activists in Raqqa describe a city where fear prevails, music has been banned, Christians have to pay religious tax in return for protection and face-veiled women and pistol-wielding men in jihadi uniforms patrol the streets. (AP Photo/militant website, File)

ISTANBUL -- A gruesome video being circulated online by Syrian activists appears to show extremists from the hardline Islamic State group stoning a woman to death in Syria’s western countryside of Hama.

In the video, a veiled woman accused of adultery begs her father for forgiveness, but he refuses. Before being tied up with a rope and led to a grave-like hole in the ground, the woman is asked if she accepts her fate. She meekly agrees. Crouching in the hole, she begins to pray out loud. The fighters, and the man said to be her father, then brutally pelt her with large rocks until she is still.

An icon showing the Islamic State’s black flag flutters in the top right corner of the screen. While some of the armed fighters have their faces covered, most of the men show their faces and do not have their voices altered -- a major difference from similar videos showing militants carrying out murders.

The WorldPost could not independently corroborate the video’s authenticity.

The self-proclaimed Islamic State -- known for its brutal war tactics, archaic and violent interpretation of Islam, and the large number of non-Syrian fighters within its ranks -- has wreaked havoc across Syria and Iraq. It has gained considerable ground, weaponry and funds in recent months, with the goal of establishing an Islamic caliphate across the region. A U.S.-led coalition has been striking Islamic State positions in Iraq and Syria, but the strikes have yet to considerably curb the group's growing power and influence.

While the video appears to be new to social media, the Syrian Observatory for Human Rights, a Britain-based monitoring group with a network of contacts in Syria, said on Tuesday it could not verify the date of the video.

A group called "Raqqa is being slaughtered silently," made up of activists in the Islamic State’s northern Syrian stronghold of Raqqa, posted the video to its Twitter page late Monday night, calling the woman’s stoning "sick." The activist group later uploaded the footage to its own website after YouTube removed the video due its graphic content.

This is not the first time brutal videos or reports of stonings at the hands of the Islamic State have surfaced.

In July, the hardline militants stoned two women to death in Raqqa, after charging them with adultery. According to reports, when the militants put one of the women into a small hole and ordered the surrounding crowd to kill her with rocks, nobody budged, so the fighters carried out the act themselves.

One month later, in August, an Iraqi taxi driver said he witnessed the militants stone a young man to death in the besieged Iraqi city of Mosul. According to him, a crowd watched as the handcuffed man, charged with adultery, was forced to the ground and hit with rocks until he was dead.