ISIS terrorists in Syria
ISIS terrorists in SyriaReuters

The Islamic State (ISIS) group has beheaded four teenagers and young men in its Syria “capital” of Raqa for allegedly providing intelligence to the American-led coalition, a monitoring group said Sunday.

The Syrian Observatory for Human Rights said ISIS beheaded them after accusing them of "photographing sites and handing information to the crusader coalition causing bombing and the death of Muslims".

"ISIS Executed 4 people they Accused them for spying for Coalition," citizen journalist group Raqa is Being Slaughtered Silently (RBSS) said on Twitter.

RBSS documents abuses in areas under IS control in Syria.

Since 2014, a U.S.-led coalition has been targeting ISIS in Syria, where the jihadists have made Raqa their de facto capital.

IS has previously carried out several beheadings in Raqa.

And last October, the decapitated bodies of two RBSS activists originally from Raqa were found in the Turkish city of Sanliurfa, 55 kilometers (35 miles) from the border with Syria's Raqa province.

ISIS is notorious for its beheadings, as it in the past released videos of its jihadists beheading Western hostages they took.

These included journalists James Foley and Steven Sotloff, and aid workers David Haines and Alan Henning.

The executioner in those videos was later identified as “Jihadi John” who was subsequently killed in a drone strike in Syria.

AFP contributed to this report.