Britain is the most outspoken proponent of nixing the arms embargo but faces opposition from some members that feel more weapons would only increase the killings and strangle hope for a negotiated settlement, Dutch Minister Frans Timmermans said.
Assad has been using extensive firepower against lightly armed rebel factions. More than 70,000 people have died since the uprising against Assad's regime erupted in March 2011.
Meanwhile, both sides have agreed in principle to enter direct talks in Geneva next month.
The date, agenda and list of participants for the conference remain unclear, and wide gaps persist about its objectives.