Syrian rebels once welcomed fighters of the jihadist Al-Nusra Front with open arms but disputes over the extremists' strict interpretation of Islam are beginning to strain the ties.
In a rebel rear base at Atme in northern Syria, on the border with Turkey, at least four fights have broken out in recent weeks between jihadists and mainstream rebels, witnesses and residents told AFP.
One fight degenerated into an exchange of fire.
While the majority of the population -- and the rebels -- are Sunni Muslims, close interaction with people from dozens of other religious groups has over centuries softened most Syrians' interpretation of Islam.
But the jihadists, who are linked to Al-Qaeda, follow a puritanical interpretation of Islamic jurisprudence, considering for example a man smoking a cigarette or choosing to shave his beard to have become "anti-Islamic".
In the village of Qah in the northwest Syria province of Idlib, Al-Nusra Front fighters arrested a man for cursing after a minor car accident, sparking a heated standoff with villagers when they brought him before an Islamic tribunal.
The arrested man was the brother of a respected local leader and longtime insurgent, who quickly mobilised dozens of armed men, residents told AFP on condition of anonymity.
After a prolonged face-off with Al-Nusra fighters during which some jihadists were kidnapped, Qah residents secured the release of the arrested man in exchange for an Al-Nusra commander.
The jihadist commander was released only after his long Salafist beard had been trimmed, the sources added.
Meanwhile, in Atme, prayer-goers stopped a Jordanian sheikh loyal to Al-Nusra from speaking at the local mosque, sparking a fist fight between locals and jihadists, residents said.
Also in Idlib province, a scuffle between protesters with opposing views on Syria's revolt broke out in rebel-held Saraqeb on Friday.
Supporters of an Islamist rebel faction tore up the flag of the Syrian revolution during an anti-regime protest filmed by activists and distributed online.
Cries of "Unity, Freedom, an Islamic state!" were met with duelling chants of "Unity, freedom, a civil state!" as the scuffle turned into a public debate on the objectives of the anti-regime uprising that broke out in March 2011.
Listed by the United States as a "terrorist" organisation, Al-Nusra Front became massively popular in several parts of Syria from about mid-2012, as their experienced fighters secured victories the mainstream rebel Free Syrian Army was slow to achieve.
The FSA's reputation was becoming tarnished with theft and corruption scandals, while the jihadists' piousness gave them an air of infallibility.
But the presence of the Al-Nusra Front on many of Syria's main frontlines also raised questions over their ultimate motivations.
Linked to Al-Qaeda in Iraq, Al-Nusra Front has claimed responsibility for the majority of suicide attacks in Syria.
Its listing in December last year as a "terrorist" group ironically galvanised support for the group.
Demonstrators chanted "we are all Al-Nusra" in several parts of Syria, with even secular activists coming out in the formidable fighters' defence.
But over time, popular support for Al-Nusra has waned.
"Every day that passes, there are incidents with these people who want to impose their way of life. They have started to be a problem for us," said an Atme local leader.
The same leader, who spoke to AFP on condition of anonymity, had recently praised the jihadists as "the only ones who came to help the Syrians, when the whole world had abandoned us".
The disputes that have arisen have had more to do with the everyday than with politics, but the over-enthusiasm of preachers -- many of them non-Syrians -- in local mosques has also led locals to turn against the jihadists.
"We accept that a (Jordanian) Al-Nusra sheikh wants to preach every once in a while. But they now want to impose their sheikh every Friday, and that's just not possible," said another Atme local leader.
"They treat some of us like unbelievers. Who do they think they are, and what gives them the right to talk to us this way?" he added.
"Why do they impose their rules on our everyday lives?"