The ISIL made the call in an audio message on Tuesday, warning other militant groups that none of them will survive.
Abu Mohammed Al-Adnani, the spokesman for the ISIL, called on its supporters in Syria to “crush them (the rival groups) totally and kill the conspiracy at birth.”
The remarks came after the al-Nusrah Front, another notorious al-Qaeda offshoot in Syria, called for a ceasefire with the so-called Free Syrian Army.
The al-Nusrah Front said that its clashes with other militant groups are benefiting the Syrian government.
The ISIL militancy is not limited to Syria, as the group is operating in Iraq at the same time. It has urged insurgents in Iraq not to lay down their weapons and continue their fight against Baghdad.
A British defense study showed last year that about 100,000 militants, fragmented into 1,000 groups, were fighting in Syria against the government and people.
The extracts of the study by defense consultancy IHS Jane’s were published on September 16, 2013.
According to the study, some 10,000 militants were fighting for groups affiliated with al-Qaeda and the rest fight for different militant groups.
The analysis also said that a large number of extremists from foreign countries are also active in Syria.
Syria has been gripped by deadly unrest since March 2011. According to reports, the Western powers and their regional allies — especially Qatar, Saudi Arabia, and Turkey — are supporting the militants operating inside Syria.
According to the United Nations, more than 100,000 people have been killed and a total of 7.8 million of others displaced due to the violence.