World leaders, including U.S. President Barack Obama and U.K. Prime Minister David Cameron, condemned a video released by the Islamic State group Friday that purportedly depicts the beheading of British aid worker Alan Henning.

The acts in the video showing Henning’s beheading -- the fourth in a series of videos focused on the executions of Western hostages by the militant group formerly known as either ISIL or ISIS -- were described variously as “barbaric,” "cowardly" and “repulsive” by political and religious leaders around the world, as follows:

British Prime Minister David Cameron

“The brutal murder of Alan Henning by ISIL shows just how barbaric and repulsive these terrorists are,” David Cameron said in a statement. “Alan had gone to Syria to help get aid to people of all faiths in their hour of need. The fact that he was taken hostage when trying to help others and now murdered demonstrates that there are no limits to the depravity of these ISIL terrorists.” Cameron said the U.K. will do “all we can to hunt down these murderers and bring them to justice.”

U.S. President Barack Obama

“The United States strongly condemns the brutal murder of United Kingdom citizen Alan Henning by the terrorist group ISIL,” the White House said in a statement. “Standing together with our U.K. friends and allies, we will work to bring the perpetrators of Alan’s murder -- as well as the murders of Jim Foley, Steven Sotloff and David Haines -- to justice. Standing together with a broad coalition of allies and partners, we will continue taking decisive action to degrade and ultimately destroy ISIL.”

United Nations Security Council

On behalf of the 15-member U.N. Security Council, Maria Cristina Perceval, who is Argentina’s permanent representative to the U.N., called the beheading a “heinous and cowardly” act. “This crime is a tragic reminder of the increasing dangers volunteer humanitarian personnel face every day in Syria,” Perceval said, according to the U.N. News Center. “The members of the council further emphasized that such continued acts of barbarism perpetrated by ISIL do not intimidate them, but rather stiffen their resolve.”

Muslim Council of Britain

Shuja Shafi, secretary general of the Muslim Council of Britain, an umbrella organization for more than 500 mosques in the U.K., said Henning’s execution was “against the spirit of Islam.” The Telegraph quoted Shafi as saying: “It is quite clear that the murderers of Alan Henning have no regard for Islam, or for the Muslims around the world who pleaded for his life. Alan was a friend of Muslims, and he will be mourned by Muslims.”

The family of Peter Kassig, a U.S. national who is being held hostage by the Islamic State group, also extended their sympathies to Henning’s family, according to BBC News. “We ask everyone around the world to pray for the Henning family, for our son, and for the release of all innocent people being held hostage in the Middle East and around the globe,” the Kassig family said in a statement released Friday.