The fighting between Ahrar al-Sham which is backed by Saudi Arabia,Qatar and Turkey and al-Qaeda-linked Hay'at Tahrir al-Sham is the the first major escalation of infighting among Takfiri groups since they reached a truce in February.
Idlib has become the base for thousands of terrorists who fled Syria's largest city of Aleppo after facing a rout against government forces in December in their worst defeat since March 2011.
Rival terrorist groups are now competing for clout in the territories they control after seeing their campaign to topple the Syrian government broadly in tatters.
On Saturday, Ahrar al-Sham said Hay'at Tahrir al-Sham, also known as HTS, was sending reinforcements to the town of Saraqeb and the Jabal al-Zawiya region in preparation for an attack, accusing the group of acts of "tyranny".
The Ibaa News Agency of HTS, instead, accused Ahrar al-Sham of setting up checkpoints and detaining one of its commanders and his bodyguard.
The so-called Syrian Observatory for Human Rights, a UK-based monitor which is sympathetic to militants, said the two groups had clashed near the village of Tel Touqan.
More clashes loom as the two sides are rushing their fighters to the frontlines, with the US news agency Associated Press expressing worries that the infighting could affect their fight against Syrian forces who have been gaining ground over the past year.
Further confrontation could also draw other terrorist groups into the infighting, especially after Hay'at Tahrir al-Sham reported the deaths of two more members near the Sarjeh village and blamed Suqour al-Sham, a strong Ahrar al-Sham ally.
Hay'at Tahrir al-Sham is part of a Takfiri coalition spearheaded by Jabhat Fateh al-Sham, which was formerly known as al-Nusra Front or al-Qaeda’s Syria offshoot.
Due to the barbarity of their actions, al-Nusra and Daesh are not subject to an all-Syria truce deal clinched late last year with the mediation of Russia, Iran and Turkey.