ANTAKYA, TURKEY // Syrian rebel fighters have accused the Muslim Brotherhood of undermining the revolt against Bashar Al Assad and trying to dictate opposition politics.
Rebel officers said the Brotherhood was putting narrow factional politicking over the broad interests of the revolt.
"We hold you responsible for delaying victory of the revolution and the fragmentation of the opposition," the Joint Command of the Free Syrian Army said in an open letter to the Muslim Brotherhood.
There was a "deep confrontation" within the opposition between the Muslim Brotherhood and other secular, national and military factions, the FSA said.
Anti-Brotherhood sentiments, particularly in Damascus, were running high, the FSA warned, with growing anger at efforts by the group to control military and humanitarian relief efforts administered by the Syrian National Coalition, the opposition bloc given Syria's seat in the Arab League at a summit last week.
A significant majority of its members are directly or indirectly allied to the Muslim Brotherhood, much to the dismay of other rebel factions who say the group's representation in the SNC political chambers vastly outweighs its street presence inside Syria.
The SNC was thrown into disarray last week by the resignation of its president Moaz Al Khatib, a move prompted at least in part by factional infighting and efforts by what he called 'old guard' opposition figures - code for the Muslim Brotherhood - to dominate the coalition by preventing new, grassroots revolutionary groups from being offered membership.
In the aftermath of that resignation, some activists and FSA units in Damascus said they would be willing to split from the SNC and follow Mr Al Khatib if he decided to go it alone.
The SNC has refused to accept its president's resignation and, despite the odd position of technically having quit, Mr Al Khatib nevertheless took part in the Arab League conference in Doha last week, filling the seat that would once have been taken by Mr Al Assad's government.
Much of the internal political manoeuvring within the opposition has remained behind the scenes, shrouded in a fog that is hard to penetrate. The eight-point FSA statement, signed by Fahad Al Masri, the Joint Command's official spokesman, brought at least some the dirty laundry out into the open.
It underlined a previous FSA warning that Ghassan Hitto, selected by the National Coalition to head an opposition government inside northern Syria, would not get its support because he was not a consensus candidate.
"This revolution is not your property and you did not make it. The revolution has been made by the people who are paying with their blood and lives," the FSA statement said.
Unflinching in its criticism, it said the Muslim Brotherhood should not treat people as if they were stupid and that its actions had thrown a roadblock in front of efforts to defeat Mr Al Assad.
It stressed that Syria's multisectarian, multiethnic demography meant no single group could or should seek to monopolise power, and that Syrians would accept only genuine equality among themselves, not the subservience of one group to another.
The Muslim Brotherhood has its role to play, the FSA Joint Command said, but should not overplay its hand or marginalise other groups.
In a response posted online, the Brotherhood spokesman Amr Mishoh dismissed the statement. He said there was no evidence for its claims and that the organisation was playing a proportionate, constructive role both in opposition politics and on the ground.
"All of these attempts to deform the Muslim Brotherhood will not succeed and will not stop our patriotic role in the Syrian revolution," he said.
More tellingly, the Brotherhood claimed the FSA Joint Command's open letter represented only Mr Al Masri, who signed it - not the FSA as a whole or the alliance of armed rebel groups.
Just as the Brotherhood's critics can accuse it of having little sway on the ground inside Syria, so the Joint Command of the FSA is, to a greater or lesser degree, something of a fiction.
Despite the corporate branding of the FSA, it is really more of a loosely knit umbrella organisation containing various armed factions that pay only lip service to the idea of a unified chain of command.
The most powerful and effective fighting units, controlled and manned by Islamists, do not take orders from distant FSA commanders.
"It's true that some FSA units, especially in Damascus, are unhappy with the Muslim Brotherhood but there are armed units elsewhere which are backed by the Brotherhood and which are loyal to them," said a leading activist in the Syrian capital.
"The divisions inside the opposition are real and seem to be getting worse, they have started breaking out into the open more and more," he said.