Still image from video of Maaz al-Kassasbeh's brutal execution
Still image from video of Maaz al-Kassasbeh's brutal executionReuters

AFP has rounded up the hit list of known killings by terrorists or movements linked to the jihadist Islamic State (ISIS) group, which announced Sunday it had beheaded 21 Egyptian Coptic Christians in Libya.

ISIS, accused of crimes against humanity by the United Nations, has stepped up atrocities, including beheadings, abductions and crucifixions, in the regions of Iraq and Syria it controls. Even so, a UN report last September revealed Syrian President Bashar al-Assad was responsible for more atrocities than ISIS.

The list starts last August 19, when ISIS posted a video of the decapitation of US freelance photojournalist James Foley, 40, who was seized in northern Syria in November 2012. It threatened to execute a second US journalist, Steven Sotloff, 31, in response to US strikes on jihadist positions in Iraq, which began in August.

On September 2, ISIS said in another propaganda video that it had beheaded Sotloff, a freelance reporter kidnapped on August 4, 2013, in Aleppo.

Then on September 13, the group claimed to have beheaded British aid worker David Haines, 44, who was seized in March 2013 while working for a Paris-based non-governmental organization.

But it wasn't only ISIS doing the beheading - on September 24, the affiliated group Jund al-Khilifa, or "Soldiers of the Caliphate," said in a video it had decapitated French tourist Herve Gourdel, 55, who was abducted in Algeria.

Then on October 3 ISIS released a video saying it beheaded British aid volunteer Alan Henning, 47, in Syria, in revenge for British strikes on jihadist positions in Iraq.

ISIS then claimed to have killed Peter Kassig, 26, an American aid worker kidnapped in Syria, on November 16 as a warning to Washington. The same video showed the gruesome simultaneous beheadings of around 15 men described as Syrian military personnel.

Moving up into 2015, the Libyan branch of ISIS said on January 8 it had killed Tunisian journalists Sofiene Chourabi and Nadhir Ktari, missing in eastern Libya since September.

On January 24 and 31, two ISIS videos claimed the beheading of Japan's Haruna Yukawa, 42, and his friend and fellow captive, journalist Kenji Goto, 47.

Jordanian pilot Maaz al-Kassasbeh, 26, on February 3 was shown in an ISIS video being burned alive in a cage after being captured in December when his F-16 crashed in Syria during a mission with the US-led coalition. His brutal murder apparently occurred well before the film was released.

An ISIS video on Sunday showed the beheading of 21 Egyptian Coptic Christians in Libya, saying they had been killed for their faith.

In addition to the murders committed by ISIS, the group on February 6 announced the death of American aid worker Kayla Mueller, 26, saying she had been killed in a coalition air strike in northern Syria. On February 10 her death was confirmed by her family and the White House, which denied that she was killed in a raid.

How do the ISIS atrocities break down state by state?

In Syria, the Britain-based Syrian Observatory for Human Rights says that from June to November, 2014, ISIS killed nearly 1,500 people, mostly civilians.

In Lebanon, the army has fought jihadists from neighboring Syria in the east. Twenty-five soldiers and police were abducted in August 2014 by ISIS and Nusra Front, the Syrian branch of Al-Qaeda. Four have been murdered.

An in Iraq, the UN High Commissioner for Human Rights in January denounced the "monstrous" contempt for human life there of ISIS, which has killed dozens of civilians this year.