Foreign Secretary William Hague has warned that extremism in Syria could flourish if the European Union refuses to ease an arms embargo preventing the supply of weapons to rebels opposed to Bashar Assad.
Speaking in Brussels ahead of a meeting of EU foreign ministers, where he will attempt to persuade his counterparts of the need to lift restrictions on the supply of weapons, Mr Hague said the current state of affairs could not be allowed to continue.
The EU embargo expires at the end of the month and Mr Hague indicated that each country would be able to adopt its own approach if no common position could be established to replace the current sanctions regime.
The UK and France have led calls for the embargo to be relaxed, but Mr Hague acknowledged their position did not have universal support within Europe.
Mr Hague insisted that amending the embargo would force Assad's regime to take peace talks seriously.
He said: "There is a difference over what it's appropriate now for the EU to do. In our view it's important to show that we are prepared to amend our arms embargo so that the Assad regime gets a clear signal that it has to negotiate seriously.
"Therefore for us amending the embargo is part of supporting the diplomatic work to bring about the political solution.
"We also have to think about what is happening to people in Syria, how long can we go on with people having every weapon that's ever been devised dropped on them while most of the world denies them the means to defend themselves.
"That is creating extremism, it is radicalising people. We are reaching the limit of how long we can go on with that situation."
With the possibility of the current regime expiring without a replacement, Mr Hague told reporters: "It is important that we are doing the right thing for Syria, that is more important than whether the EU is able to stick together on every detail of this.
"I think we will have to see how the discussion goes, but we are prepared for every eventuality."
He added: "Of course it is preferable for an EU policy to be able to continue. But for that we have to have sufficient agreement on the basis of that policy."We have tried on all previous occasions on this to make sure that there is still a common EU policy but if we can't have one in the future then each country will have to ensure it has its own sanctions or the sanctions regime will have to be reconstructed for the future.
"But we are looking for common ground in this meeting, of course it is preferable to keep that policy together if we can."
Reza Afshar, the head of the Foreign Office's Syria team, wrote on Twitter that the EU faced a "strategic decision" today: "Give hope to political track on £Syria by amending arms embargo; or kill off political track."
Shadow foreign secretary Douglas Alexander said: “As William Hague meets EU foreign ministers today, he should be asking both is it legal, and is it advisable to send arms to Syria's rebels.
” How would the Government prevent British-supplied weapons falling into the wrong hands, and how does supplying weapons help to secure a lasting peace.
“Syria today is awash with arms and in the House of Commons last week MPs on all sides expressed real concern about the identity, intent and tactics of some of the rebel forces.
“In Washington the Prime Minister clearly failed to convince president Obama of his case, so today in Brussels the UK's use of the veto would confirm that the Prime Minister had also failed to convince our European partners.”
Anna Macdonald, head of arms control at Oxfam, warned that supplying weapons would mean "adding fuel to the fire" in Syria.
She told BBC Radio 4's Today programme: "We are concerned that supplying arms to the opposition won't level the playing field, in fact it will fuel a deadly arms race that will have even worse consequences for civilians.
"The millions of people suffering in Syria right now don't need more arms, they need aid."
She added: "Providing more arms in times of conflict is simply adding fuel to the fire, it's fanning the flames of conflict and making the situation much worse."
The peace process must be "exhausted" before any other solutions were considered, she added.