German Foreign Minister Guido Westerwelle said on Saturday the Syrian opposition must distance itself from extremist forces and he said Germany was skeptical about supplying weapons to the rebels.
"We expect from the opposition that they clearly distance themselves in Syria from terrorist and extremist forces," Westerwelle told reporters in Istanbul at a meeting of Syrian opposition leaders and their international backers.
"We are skeptical as the German government when it comes to delivering weapons because we are concerned that weapons could fall into the wrong, namely extremist, hands, but it is a matter that must now be discussed in the European Union."
A U.S. official said on Friday Washington planned to provide about $100 million in new non-lethal aid to the Syrian opposition that could include for the first time battlefield support equipment such as body armor and night-vision goggles.
Secretary of State John Kerry was expected to announce the new aid package, which would mark a recalibration of U.S. policy toward Syrian rebel groups at Saturday's meeting. Fresh U.S. humanitarian aid for Syrian refugees is also likely.
The new assistance would stop short of supplying weapons to rebels fighting to overthrow Syrian President Bashar al-Assad. It is also far less than what is sought by Syrian opposition leaders, U.S. allies Britain and France and some U.S. lawmakers.
The 11-nation "core group" of the Friends of Syria, including the United States, European and Arab nations, has been deadlocked over how to remove Assad, whose security forces killed and arrested thousands of protesters who took to the streets to demand democratic reforms in March 2011.
Syria's opposition has said it hopes the Istanbul meeting will give teeth to a tacit agreement that arming rebel groups is the best way to end Assad's rule.
More than 70,000 have been killed in the revolt and subsequent civil war. But a military stalemate has set in and much of Syria is left in ruins because of a divided and ineffective opposition, a lack of action by foreign allies and Assad's ability to rely on support from Russia and Iran.