Clashes erupted in Aleppo on Monday between Syrian regime forces, according to the Syrian Observatory for Human Rights.
Aleppo, Syria's largest city and former commercial capital, was recaptured by President Bashar Al Assad's forces in 2016, which made it the regime's most vital gain so for far in a war that has claimed hundreds of thousands of lives.
"Sporadic clashes took place after midnight in the northern countryside of Aleppo, between regime forces, militiamen loyal to them and local factions," the Observatory said in a statement, without specifying the names of the groups.
According to local activists, the skirmishes were between the Barri clan and the Kafariya and Foua militias.
Members the Barri clan clashed with the militias over properties belonging to internally displaced Syrians that were seized by the Kafariya and Foua fighters, Mansour Hussein, a reporter in Aleppo and member of the Syrian Human Rights organisation, told The National.
"Violent clashes broke on Sunday night, machine guns were used, particularly in Marji and Moyassar areas," Mr Mansour said.
"The Kefraya and Al Foua gangs seized control of the Free Syrian Army and civilian houses, which were outside the city, in neighbourhoods where the Barri clan are most active," he said.
Both of these militias have taken control over regions the Barri clan consider their own and claim they have precedence on the land there as they fought against the Free Syrian Army to regain control of the area.
Hassan Shaaban Barri, a member of the clan, denied the reports however, telling The National that the groups are united and working "hand in hand".
A member of the Syrian parliament for Aleppo, Fares Shehabi, said the Barri clan has no affiliation with any militia.
"I haven't heard of this, especially in Aleppo, these reports are fake," he told The National.
Russia and Iran have provided massive aid to Assad's forces, allowing them to advance on a number of fronts in recent years, especially in Aleppo.
The Barri clan is strongly pro-government. It was the first to establish local militias in the eastern districts of Aleppo in 2012, and fought alongside the regime to regain control of rebel-held areas.
The groups have fighters recruited into the Iranian-backed Local Defence Forces in Aleppo, Aymenn Al Tamimi, research fellow at Middle East Forum, told The National.
"Although there isn't enough evidence to suggest that the fighting in Aleppo is actually occurring between the groups, in many areas there have been personal quarrels that arise between members of different formations," Mr Al Tamimi said.
An example would be in Albukamal between members of the North Defence Forces and some fighters recruited into the Islamic Revolutionary Guards Corp’s forces, he said.
"You could see more instances of that if front lines remain frozen and efforts are not directed at common enemies," Mr Al Taimimi added.
Mr Al Assad remains firmly in power seven years after an Arab-inspired uprising that began with peaceful protests but escalated into a devastating civil war.
Rebels who have held the eastern part of the city since the early days of the war have now lost most of their besieged enclave to pro-Assad forces.
Additional reporting by Sunniva Rose