The US says it has suspended all non-lethal assistance to rebels in Syria after jihadists seized depots and supplies belonging to the opposition front.
The US has suspended all non-lethal aid to the opposition in northern Syria after Islamist rebels seized key bases and warehouses belonging to the Western-backed Free Syrian Army (FSA), a US official says.
"We have seen reports that Islamic Front forces have seized the Atmeh headquarters and warehouses belonging to the Supreme Military Council and we are obviously concerned," TJ Grubisha, spokesman for the US embassy in Ankara, told AFP.
"Because of the current situation, the United States has suspended deliveries of non-lethal assistance into northern Syria," he said.
The Islamic Front, the largest Islamist rebel force in Syria, seized depots belonging to the FSA near the Bab el-Hawa border crossing with Turkey on Saturday.
The group also took control on Tuesday of the crossing itself, the monitoring group Syrian Observatory for Human Rights said.
Non-lethal aid provided to the rebels by Washington has included armoured vehicles, night vision goggles, laptops and advanced communications equipment.
Grubisha said the US decision to suspend such aid would not impact humanitarian assistance that was co-ordinated by international and non-governmental organisations including the United Nations.
"We are gathering the facts and consulting with friends of the Syrian opposition on next steps in support of the Syrian people," Grubisha said.
"We are working with General Idriss and SMC staff to inventory the status of US equipment and supplies provided to the SMC," he added, referring to the Supreme Military Council of the FSA headed by Selim Idriss.
State Department spokeswoman Jen Psaki said news that "the headquarters and warehouses belonging to the SMC have been taken over is certainly something concerning".
US support for Idriss remained strong, she stressed, and although it was unclear when deliveries would resume "it's in our interests and the international community's interest to ... have the aid going through this area as soon as we can.
"But we want to evaluate the circumstances on the ground and make a decision from there," Psaki added.
Britain said it too had suspended non-lethal aid, with a spokesman for its Ankara embassy saying the decision was taken because "the situation remains unclear" and did not mean support for the opposition was diminishing.
France said it would continue to provide non-lethal military aid to the main opposition National Coalition in coordination with its partners in the European Union.
The Islamic Front was formed last month when six groups merged and pledged to work towards forming an Islamic state. It has rejected the authority of the FSA.
Turkey on Tuesday shut its side of the border in Hatay province after the Islamic Front seized the Bab al-Hawa post, customs officials said in a statement.
"The crossing into Syria via Cilvegozu has been closed ... due to the clashes between rebel groups in Syria," the statement said.
But a foreign ministry official, contacted by AFP, said the measure was temporary and would not affect refugees entering Turkey.
Turkey, which is fiercely opposed to the regime of President Bashar al-Assad, has taken in about 600,000 refugees from the Syrian conflict and has become a base for Syrian rebels and army defectors who form the core of the FSA.
The FSA was the first organised rebel military entity to emerge after peaceful demonstrations against the Assad regime in 2011 degenerated into an armed uprising.
Since then, numerous other groups have emerged, many of them Islamist, which are operating with a high degree of autonomy from the FSA, if not totally independently.