Salim Idris, the chief of staff of so-called Free Syrian Army, told the Telegraph that Britain has not agreed to provide firepower, despite orchestrating the lifting of a European Union arms embargo on Syria.
"There are no assurance at all," said General Idris. "They [Britain] promised to give us arms. But after lifting of arms embargo we have not receive any signals that we are going to be supported."
For more than two years, the insurgency in Syria, supported by Saudi Arabia and Qatar, made no progress.
A change in the military tide in recent months, with President Assad bolstered Russian weapons has left the militant Free Syrian Army in a very "dangerous position" and unable them to win the foreign-backed war.
" The FSA is receiving very little and what we are receiving is not enough to bring an end to the fight in Syria," said General Idris.
“What we need most are top range anti-tank weapons,” said General Idris, adding that the traditional rocket-propelled grenades the rebels were currently using against tanks were no longer effective.
Many militant commanders in Syria have become so disillusioned with this hesitation that they have "washed their hands" of foreign military and diplomatic interferences.
A key Syrian Revolution General Commission bloc within the main opposition front withdrew earlier, accusing its leaders of misusing funds and being motivated by personal ambition.
London says it does not yet know whether it will arm Syrian terrorist groups and a decision will be delayed until after the planned Geneva talks on Syria.
British Foreign Minister William Hague said in an interview with German daily Frankfurter Allgemeine Zeitung that London believes efforts to bring representatives of the Syrian government and foreign-backed armed groups round the negotiating table should continue, though he said he is not “overly optimistic”.
"A decision on whether to deliver lethal weapons will depend on how those negotiations go and other countries' attitudes," he said.
Russia and the US said last month that they want a conference on Syria to be held in Geneva but no date is yet set for the event.
Hague’s remarks come after the EU did not extend an arms embargo on Syria last month, allowing governments, such as London and Paris, to consider direct arming of Syrian terrorists following months of reported covert arms deliveries to Syrian militants.