And this is on top of the the two FSA brigades that recently defected to al-Nusra Front and pledged allegiance to al-Qaeda.

(Reuters) – Thousands of Syrian rebels have broken with the Western-backed coalition to form a new Islamist force that may pressure President Bashar al-Assad but also undermine the West’s hopes of putting its friends in his place.

Ever more divided on a battlefield where Assad’s better armed troops have been gaining ground, allies of the Free Syrian Army (FSA) were among 13 disparate rebel factions to disown the exile leadership and support an Islamic alliance that includes the al Qaeda-linked Nusra Front, commanders said on Tuesday.

Details of the numbers of fighters involved and of how they would cooperate remained unclear. But, in an online video, a leader of the Islamist Tawheed Brigade said the bloc rejected the authority of the Syrian National Coalition (SNC) and the Western- and Saudi-backed exile administration of Ahmad Tumeh.

It is a setback for foreign leaders trying to bolster more secular rebel groups and to reassure voters skeptical of deeper involvement in Syria’s civil war. Some may think again about help for the fighters, which ranges from weaponry from the Gulf to non-lethal aid from Europe and the United States.

The 13 groups signed a statement calling for the opposition to Assad to be reorganized under an Islamic framework and to be run only by groups fighting inside Syria. Signatories range from hardliners like the Nusra Front and Ahrar al-Sham to more moderate groups such as the Tawheed Brigade and Islam Brigade.

“These forces feel that all groups formed abroad without returning to the country do not represent them, so the forces will not recognize them,” said the statement read online by Abdulaziz Salameh, the political leader of the Tawheed Brigade.

“Therefore the National Coalition and its supposed government led by Ahmad Tumeh do not represent them and will not be recognized,” he said.

More on the groups joining forces:

Abdelaziz Salame, the highest political leader of the Tawhid Brigade in Aleppo, has issued a statement online where he claims to speak for 13 different rebel factions. You can see the video or read it in Arabic here. The statement is titled “communiqué number one” – making it slightly ominous right off the bat – and what it purports to do is to gut Western strategy on Syria and put an end to the exiled opposition. […]

The following groups are listed as signatories to the statement.

Jabhat al-Nosra
Islamic Ahrar al-Sham Movement
Tawhid Brigade
Islam Brigade
Suqour al-Sham Brigades
Islamic Dawn Movement
Islamic Light Movement
Noureddin al-Zengi Battalions
Haqq Brigade – Homs
Furqan Brigade – Quneitra
Fa-staqim Kama Ummirat Gathering – Aleppo
19th Division
Ansar Brigade

Who are these people?

The alleged signatories make up a major part of the northern rebel force, plus big chunks also of the Homs and Damascus rebel scene, as well as a bit of it elsewhere. Some of them are among the biggest armed groups in the country, and I’m thinking now mostly of numbers one through five. All together, they control at least a few tens of thousand fighters, and if you trust their own estimates (don’t) it must be way above 50,000 fighters.