A video circulating on social media shows a masked figure threatening that “rivers of blood will flow” at the upcoming Olympics in Paris, which Israel is set to compete in.

In the minute-long clip released on Tuesday, an Arabic-speaking man whose face is concealed by a keffiyeh addresses “the people of France and the French President [Emmanuel] Macron” and warns them that they will be punished for supporting “the Zionist regime in its criminal war against the people of Palestine.”

“You provided Zionists with weapons, you helped murder our brothers and sisters, our children,” the man, standing before a slate grey background, says to the camera. “You invited the Zionists to the Olympic games. You will pay for what you have done.

Wearing dark attire and a Palestinian flag over his chest, the man continues: “Rivers of blood will flow through the streets of Paris. This day is approaching, God willing. Allah is the greatest.”

The video, originally posted on an Egyptian news website, concludes with the masked man holding up a fake severed head.

Though speculators have been quick to pin responsibility on Hamas, the video does not provide any indication of the group behind it, nor does the figure bear any emblems – like the traditional green headbands – worn by Hamas militants and it has not been shared on official Hamas channels.

Though the veracity of the clip remains unclear, it does little to assuage fears of terrorist attacks and other security risks at the upcoming summer Olympics in the French capital, which are set to be the most heavily policed games in the modern era.

The Olympics have been a target for attacks in the past, notably the 1972 Munich Games where 11 Israeli athletes and coaches were killed by members of the Palestinian terrorist group Black September. During the 1996 Atlanta Games, a bomb killed one woman and injured more than 100 people.

For the protection of Israeli athletes, an elite French anti-terrorist unit will be deployed to provide a “ring of steel” around Israel’s first event at the Paris Olympics, and armed Israeli agents have also been sent to Paris amid tension over the Israel-Hamas conflict and calls for pro-Palestine demonstrations.

France plans to deploy 35,000 police officers for each day of the event, with 45,000 due to be present for the Opening Ceremony, according to a report from CNN.