Dutch intelligence services said Tuesday they were investigating reports that eight Dutch citizens have been executed in Syria by Islamic State group (IS) after they tried to quit the militants group.
"We are investigating the signals from this open source to get further confirmation," a spokesperson for the Dutch AIVD intelligence sources told AFP, adding they had no further information.
Syrian activists on Monday said via Twitter that "Daesh executed eight Dutch fighters on Friday in Maadan, Raqa province, after accusing them of attempting desertion and mutiny."
Daesh is another name for IS group.
The tweet was posted by Abu Mohammad, a member of the citizen journalist group Raqa is Being Slaughtered Silently (RBSS), and has not been confirmed by any other source.
The group said in a statement that the eight were "then buried... in the mountain in Aljerf area, after being accused of incitement against IS group."
RBSS has been documenting since April 2014 abuses in Raqa, the group's de-facto capital in northern Syria.
Tension has boiled in Raqa over the past month between 75 Dutch militants-- among them fighters of Moroccan origin -- and IS group intelligence operatives from Iraq, RBSS said.
Three other Dutch militants were arrested by Iraqi IS group members who accused them of wanting to flee and one of the detainees was beaten to death during the interrogation, according to RBSS.
According to past estimates by the Dutch secret services, 200 people from the Netherlands including 50 women have joined IS group in Syria and Iraq.