BEIRUT -- The United States and Britain said Wednesday that they were suspending deliveries to rebels in northern Syria of nonlethal aid such as communications equipment and laptops after some of the gear was seized by Islamic militants.
The decision reflected fears of the growing strength of al-Qaida-linked forces among the rebels in the civil war, complicating the West's goal of bolstering the moderate opposition and persuading President Bashar Assad to step down.
Humanitarian aid such as food and blankets would not be affected, officials said, as a blustery storm dumped snow and torrential rain in the region and plunged temperatures below freezing, heaping more misery on refugees inside and outside Syria.
The suspension dealt another blow to the Syrian opposition, highlighting diminishing international support for their cause as the extremists rapidly expand their hold across rebel-held territories.
The U.S.-Britain decision comes a few days after ultraconservative opposition factions took control of Free Syrian Army bases and warehouses containing lethal and nonlethal weapons at the Bab al-Hawa crossing between Syria and Turkey. The bases belonged to the FSA's Supreme Military Council, led by Gen. Salim Idris, a secular-minded, Western-backed moderate.
Their takeover by the Islamic Front, a new alliance of six of the most powerful Islamic rebel groups in Syria, was an embarrassing setback for Gen. Idris, who has seen his influence greatly diminished by the rise of al-Qaida affiliated militants flush with cash, weapons and battleground experience.
"We have seen the reports that Islamic Front forces have seized the headquarters in question and warehouses belonging to the Supreme Military Council, and we're obviously concerned by those reports," White House spokesman Josh Earnest said in announcing the suspension. "We're still gathering facts and consulting with Gen. Idris and the Supreme Military Council staff to inventory the status of U.S. equipment and supplies that have been provided to the SMC."
State Department spokeswoman Jen Psaki said U.S. assistance "continues through other neighboring countries to other parts of Syria."
Britain's Foreign Office said it "will not be making any deliveries of equipment" to the FSA while it investigates those attacks. It said it intends to resume assistance as soon as conditions on the ground allow for its "safe delivery."
Turkey said it was shutting its side of the border in response. A statement issued by the ministry of customs and trade confirmed the closure Tuesday, saying the Syrian side of the Bab al-Hawa crossing was now in the hands of the Islamic Front.
Capt. Islam Alloush, a military spokesman for the Islamic Front, denied that fighters of the group had forcefully taken over the SMC warehouses. "This is a lie," he said in an interview via Skype. He said fighters from the Front, which include the ultraconservative Ahrar al-Sham faction, had received a call from Gen. Idris' office, asking for assistance after they came under attack by unknown gunmen. When the fighters reached the area, he said, they found the warehouses emptied and that SMC guards and officers had fled.
Gen. Idris and other FSA officials could not be immediately reached for comment.
More than 100,000 people have died in Syria's civil war, now in its third year. With just about a month to go before the start of internationally brokered peace talks to end the civil war, Mr. Assad's forces have stepped up a punishing offensive against rebels in a mountainous region near the border with Lebanon. The fractured opposition has been losing ground militarily, as rebel factions turn their guns against each other, and the rise of al-Qaida linked factions has diminished international confidence in the rebels and undermined the battle against Mr. Assad.
Some of the six rebel groups in the Islamic Front were once part of the FSA.