By Dasha Afanasieva and Dominic Evans
ISTANBUL/BEIRUT (Reuters) - Syria's Western-backed opposition said on Thursday its military arm had invited Islamist fighters to secure its weapons depots on the Turkish frontier after an attack by al Qaeda militants.
The United States and Britain suspended non-lethal aid to northern Syria after reports that Islamic Front forces had taken buildings belonging to the coalition's Syrian Military Council (SMC) in Bab al-Hawa on the border with Turkey.
But the opposition Syrian National Coalition said the SMC had in fact asked the Islamic Front, a union of six major rebel groups, to defend the premises against fighters from the al Qaeda-affiliated Islamic State of Iraq and the Levant (ISIL).
"The SMC warehouses were overrun by ISIL ... As a result of that, (SMC leader) General Salim Idris sent a request to the Islamic Front to protect these warehouses," coalition spokesman Khaled Saleh said in Istanbul.
"The Islamic Front came in and managed to push ISIL back and they are waiting for General Idris's group to come and take control of their warehouses," he said.
A media officer in the coalition said that after taking control of the two warehouses, the Islamic Front had given Idris an inventory of their contents. One warehouse was reportedly empty and the other contained ammunition and paramilitary equipment.
The U.S. and British aid cut-off underlined a crisis in the rebel leadership, which seeks international backing to reinforce its credibility and stop fighters joining al Qaeda-backed groups now leading the struggle against President Bashar al-Assad.
The SMC's inability to control its own storehouses without help from Islamist groups has exposed its military weakness.
Idris was in Reyhanli in southeast Turkey on Thursday meeting Islamic Front brigade leaders, the media officer said, adding that both sides were agreed that control of the warehouses would be handed back to Idris once he has enough troops available to protect them.
Abu Talha, an Islamic Front leader, confirmed his fighters had been responding to the SMC's plea for help. "In truth, the call came a bit late," he told al Jazeera television.
"There was more than one case of theft or looting from the Command and unfortunately the Supreme Command doesn't have the power yet to defend its weapons depots and its bases," he said, referring to the SMC, which the West has tried to build up as the body in overall command of the campaign to topple Assad.
For months rebel leaders have discussed how to restructure the SMC into a more organized body which would give the Islamic Front representation reflecting its presence on the ground.
But with hundreds of brigades to be consulted, progress has been slow and the Bab al-Hawa standoff is a new hindrance, rebel sources said.
(Editing by Nick Tattersall and Alistair Lyon)