Senior Islamic State (Isis) commander Omar al-Shishani is "clinically dead" after a US air strike in northern Syria. After days of uncertainty surrounding his death, the head of the Syrian Observatory for Human Rights confirmed that the warlord is in critical condition in the group's de-facto capital of Raqqa.

The elusive Chechen, who was born Tarkhan Tayumurazovich Batirashvili in Georgia, is more commonly known by his nom de guerre Omar al-Shishani. There has been several rumours about his death and capture since 2014, with Chechen leader Ramzan Kadyrov declaring him dead in November 2014.

Al-Shishani most recently held the role of chief of staff in the military council for the extremist organisation before being targeted in a barrage of air strikes on the Syrian town of al-Shadadi on 4 March. US officials said a few days later that the red-bearded jihadist "likely died" in the strike in northeastern Syria.

It seems al-Shishani survived the attack, but has been left "clinically dead" after his convoy was targeted. "Shishani is not able to breathe on his own and is using machines. He has been clinically dead for several days," said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, according to an Al Arabiya report.

Rahman said al-Shishani was "the ISIL (IS) equivalent of the secretary of defence". The 29-year-old Daesh (IS) leader was one of the most wanted Jihadists by Washington, which put a $5m (£3.5m) bounty on his head.

Known for his signature red beard, he is a veteran of the 2008 Russo-Georgian War and has risen up the ranks of IS after previously being the leader of a rebel group of foreign fighters known as Katibat al-Muhajireen (Emigrants Brigade), which was battling Bashar al-Assad's troops in northern Syria.

Al-Shishani was once the leader of the Jaish al-Muhajireen wal Ansar in Syria before joining IS. He is said to have been a disenfranchised former Georgian soldier, who was discharged from the army after contracting tuberculosis.

He grew increasingly disillusioned by life at home, unable to find a job after his mother passed away from cancer. Al-Shishani was arrested for gun running and was imprisoned. In 2012, he left Georgia to head to Turkey and later Aleppo to fight in the Syrian civil war.

Just before his appointment as northern commander for IS in Syria, the Chechen masterminded the capture of Menagh Air Base in August 2013, which boosted his standing among comrades. Since 2013, he has had authority over conflicts in Raqqa, Lattakia, and northern Idlib.