Any move to arm the Syrian opposition by the West would dangerously escalate the violence in the region and risk weapons falling into militant extremists, senior MPs have warned.
On Tuesday William Hague announced the UK and France had managed to strong-arm the EU into lifting its arms embargo on Syria - allowing London and Paris to begin delivering weapons to opponents of president Assad.
Hague has insisted "no immediate decision" to arm the rebel groups had been made but if it were it would be done in "carefully controlled circumstances".
The foreign secretary insisted safeguards were in place to ensure that any equipment delivered to the region "would only be supplied to the National Coalition, for the protection of civilians".
However John Baron, the Conservative MP for Billericay and member of the foreign affairs committee, said the idea the West could keep track of who got their hands on its weapons "beggars belief".
"Trying to track and trace sophisticated weaponry is not necessarily easy. The best way of doing it is having people on the ground to regulate it, but then you are talking about putting your own people in and that then takes this into another story," he said.
He told The Huffington Post UK: "The idea we can track and trace weapons and delineate giving them to good guys and not the bad guys beggars belief."
Baron, a former captain in the British army, said "pouring more arms into this conflict" would only serve to "escalate the violence" and cause more suffering.
The Tory MP, who quit the party's frontbench in 2003 over Iain Duncan Smith's support for the Iraq War, said the West should examine its own poor record of foreign interventions in recent years before getting involved in another.
"The seeds of democracy are flourishing more in the Middle East and North Africa than they are in Iraq and Afghanistan where we have paid a high price," he said.
Baron also pointed to the arming of Mujahideen and Saddam Hussain in the 1980s - decisions he said had come back to haunt the West. "Our track record when it comes to this sort of thing is pretty poor," he said.
Former Tory cabinet minister John Redwood told BBC Radio 4's World at One programme there was a "strong feeling" on the Conservative backbenches that despite may make it "worse rather than better".
He asked: "How do you identify the good rebels? Russia will escalate it if they think we are escalating it. The last thing you need is to tip more weapons into this cauldron."
And Former Liberal Democrat leader Sir Menzies Campbell, also member of the foreign affairs committee, said the decision was "gesture politics on a grand scale" that "we may live to regret".
He added: "The UK has helped to divide the EU, no matter what is being claimed to the contrary. Sooner or later weapons will be sent to the Syrian opponents of Assad with no prospect that he will be persuaded to change his stance or any guarantee that such weapons will not fall into the hands of extremists who care nothing for democracy or human rights."
However proponents of arming the rebels argue the rebels are unfairly handicapped by the EU arms embargo as the regime has been receiving weapons shipments from Russia.
Tory MP Brooks Newmark said the two years of negotiations at the United Nations had made "no progress whatsoever" in resolving the conflict. He told the BBC: "It's an asymmetrical war in which Bashar Assad has all the weapons on his side."
And addressing concerns that weapons would fall into extremists he said: "We're not talking about giving arms to the man who ate the heart of one of Bashar Assad's soldiers".
Russian foreign minister Sergei Ryabkov has accused Britain and France of "fanning the flames of the conflict" by opening up the possibility they will arm the Opposition. His criticism came as Moscow confirmed it would press ahead with the delivery S-300 anti-aircraft missiles to the Syrian regime - designed to prevent "the involvement of outside forces".